In language learning, the principal parts of a verb are the most fundamental forms of a verb that can be conjugated into any form of the verb. The concept originates in the humanist Latin schools, where students learned verbs by chanting them in the four key forms from which all other forms can be deduced, for example:
ferō – ferre – tulī – lātum ('to carry')
Not all languages have to be taught in this way. In French, for example, regular verbs can be deduced from a single form, the infinitive, and irregular verbs are too random to be systematized under fixed parts. But the concept can be carried over to many languages in which the verbs have some kind of "regular irregularity", i.e. irregularity always occurs at the same place in an otherwise regular system.
Although the term 'principal part' is usually applied to verbs, the same phenomenon can be found in some languages in nouns and other word types.
In Latin, most verbs have four principal parts. For example, the verb for "to carry" is given as portō – portāre – portāvī – portātum, where portō is the first-person singular present active indicative ("I carry"), portāre is the present active infinitive ("to carry"), portāvī is the first-person singular perfect active indicative ("I carried"), and portātum is the neuter supine. Most of the verb forms in Latin derive from the first two principal parts: portābō, "I shall carry", is derived from the root portā-, taken from the present infinitive. However, all active perfect forms are derived from the third principal part (so portāveram, "I had carried", is taken from portāv-) while the perfect participle (portātus, portāta, portātum, "having been carried") is derived from the supine and is used to form the perfect passive participle with the auxiliary verbsum (such as portātum est, "it has been carried"). The auxiliary verb is often dropped when writing poetry in Latin.
For many Latin verbs, the principal parts are predictable: portō shown above uses a single stem, port-, and all principal parts are derived from them with the endings -ō – -āre – -āvī – -ātum. Others have more complicated forms: regō ("I rule") has the perfect form rēxī and perfect participle rēctum, derived as *reg-sī and *reg-tum. A handful of verbs, such as sum – esse – fuī – futūrum ("to be"), are simply irregular.
A number of verbs have fewer than four principal parts: deponent verbs, such as hortŏr – hortāri – hortātus sum, "to exhort", lack a perfect form, as do semi-deponent verbs, such as audeō – audēre – ausus sum, "to dare"; in both cases, passive forms are treated as active, so all perfect forms are covered by the perfect participle. A handful of verbs are also defective, including the verb ōdī – ōdisse, "to hate", which only has perfect forms derived from a single stem.
Verbs in Ancient Greek have six principal parts: present (I), future (II), aorist (III), perfect (IV), perfect middle (V) and aorist passive (VI), each listed in its first-person singular form:
Part I forms the entire present system, as well as the imperfect.
Part II forms the future tense in the active and middle voices.
Part III forms the aorist in the active and middle voices.
Part IV forms the perfect and pluperfect in the active voice, and the (exceedingly rare) future perfect, active.
Part V forms the perfect and pluperfect in the middle voice, and the (rare) future perfect, middle.
Part VI forms the aorist and future in the passive voice.
One principal part can sometimes be predicted from another, but not with any certainty. For some classes of verbs, however, all principal parts can be predicted given the first one.
Germanic languages
English
Excluding four common irregular verbs, the principal parts of all other English verbs are the infinitive, preterite and past participle. All forms of these English verbs can be derived from the three principal parts. Four verbs have an unpredictable 3rd person singular form and the verb "to be" is so irregular it has seven separate forms. Lists or recitations of principal parts in English often omit the third principal part's auxiliary verb, rendering it identical to its grammatically distinct participial form. For example, the verb "to take" has the principal parts take – took – (have) taken. The verb "to bet" has bet – bet – (have) bet and the verb "to break" has break – broke – (have) broken. With irregular verbs the simple present 3S (he, she, it) is derived from infinitive+'s' with the exception of spelling changes such as catch – catches, fly – flies and teach – teaches, which follow the same rules for regular 3S verbs.
Examples of irregular verbs and their principal parts
only one part is irregular
Part
rendering
infinitive
to sew
preterite (or simple past)
sewed
past participle
sewn
both parts are irregular
Part
rendering
infinitive
to sing
preterite (or simple past)
sang
past participle
sung
all forms are the same
Part
rendering
infinitive
to cut
preterite (or simple past)
cut
past participle
cut
Regular verbs
Most verbs are regular enough that all forms can be derived directly from the infinitive. For example, the verb love derives all its forms systematically (love, loved, loving, has loved, loves), and since these can all be deduced from the basic form (the citation, dictionary, or lexicographic form, which in English is the bare infinitive), no other principal parts have to be learned. With irregular verbs like the verb sing, on the other hand, the forms sang and (have) sung cannot be deduced, so the learner of English must memorize three principal parts, sing – sang – (have) sung. The present 3S (he/she/it) is derived from the infinitive+'s' with the exception of verbs ending in a single -o, or ending in -s, -x, -z or the digraphs -sh, -ch, in which case it is derived from 'infinitive+es'. With three irregular verbs (and their derivatives) the 3S has to be learnt independently (e.g. has, does, undoes, redoes).
ends in the letter e
Part
rendering
infinitive
to score
preterite
scored
past participle
scored
other endings
Part
rendering
infinitive
to risk
preterite
risked
past participle
risked
doubling consonants
Part
rendering
infinitive
to stop
preterite
stopped
past participle
stopped
Highly irregular verbs
There are three verbs (in addition to their derivatives) with an irregular third person singular form in the present tense. As a result, three principal parts are insufficient to conjugate these fully.
to have
Part
rendering
infinitive
to have
present 3S
has (hæz)
preterite
had
past participle
had
to say
Part
rendering
infinitive
to say
present 3S
says (sɛz)
preterite
said
past participle
said
to do
Part
rendering
infinitive
to do
present 3S
does (dʌz)
preterite
did
past participle
done
To be
The verb "to be" is completely irregular having seven separate forms.
To be with seven different forms
Part
rendering
infinitive
to be
present 1S
am
present plural and 2S
are
present 3S
is
preterite 1S and 3S
was
preterite plural and 2S
were
past participle
been
German
The situation in German is very similar to English. Regular verbs require no memorizing of principal parts, since all forms can be deduced from the infinitive. However, some uncertainty may exist as to the choice of the perfect auxiliary, which could be haben ('to have') or sein ('to be'). This can be solved by memorizing the infinitive with the third-person singular perfect tense, which some teachers recommend.
tanzen – er hat getanzt
Strong verbs and irregular weak verbs are more complicated. As in English, these verbs are usually memorized by means of three principal parts: infinitive – third-person singular past tense – third-person singular perfect tense.
singen – sang – gesungen ('to sing' – a typical strong verb)
However, in order to deduce the full paradigm, learners must also know the third-person singular present and the third-person singular past subjunctive, which involve some peculiarities.
A small number of verbs have other irregularities, most of which are limited to the forms of the present tense.
Icelandic
There are four types of principal parts in the Icelandic language, determined by the type of verb:
Weak verbs
Icelandic weak verbs have the following principal parts:
It is possible to make the presentsubjunctive mood (þótt ég borði, "though I eat") from the first principal part (að borða, "to eat"). It is also possible to make the pastsubjunctive mood (þótt ég borðaði, "though I ate") from the second principal part (ég borðaði, "I ate").
In some other classes of weak verbs without 'a' as the thematic vowel, the present indicative singular undergoes more changes, but they are still to a large extent predictable.
Strong verbs
Icelandic strong verbs have the following principal parts:
It is possible to make the presentsubjunctive mood (þótt ég finni, "though I find") from the first principal part (að finna, "to find"). It is also possible to make the pastsubjunctive mood (þótt ég fyndi, "though I found") from the third principal part (við fundum, "we found").
The present singular indicative in this class also undergoes more changes (i-umlaut, dental suffix assimilation etc.), which may let some verbs seem irregular at first glance. They are, however, mainly regular changes, like those in the weak verbs.
It is possible to make the presentsubjunctive mood (þótt ég kunni, "though I knew") from the first principal part (að kunna, "to know"). It is also possible to make the pastsubjunctive mood (þótt ég kynni, "though I knew") from the third principal part (ég kunni, "I knew").
Ri-verbs
Icelandic Ri-verbs have the following principal parts:
It is possible to make the presentsubjunctive mood (þótt ég snúi, "though I turn") from the first principal part (að snúa, "to turn"). It is also possible to make the pastsubjunctive mood (þótt ég sneri, "though I turned") from the second principal part (ég sneri, "I turned").
Excluding a few highly irregular verbs, in Spanish, verbs are traditionally held to have only one principal part, the infinitive, by which one can classify the verb into one of three conjugation paradigms (according to the ending of the infinitive, which may be -ar, -er or -ir). However, some scholars believe that the conjugation could be regularized by adding another principal part to vowel-alternating verbs, which shows the alternation. For example, herir "to hurt" is usually considered irregular because its conjugation contains forms like hiero "I hurt", hieres "you hurt", where the vowel in the root changes into a diphthong. However, by including the first person singular, present tense, indicative mood form (hiero) as a principal part, and noting that the diphthong appears only when that syllable is stressed, the conjugation of herir becomes completely predictable.
French
Regular verbs are formed from a single principal part (the infinitive), and all conjugations derive from this one principal part. A handful of verbs require spelling changes in which case it can be considered that these verbs technically have two or three principal parts depending on how many spelling changes need to be made. They include doubling a consonant, adding accent markers, adding the letter e, and converting letters for example y becoming i.
Seven principal parts
Irregular verbs are markedly more complicated, requiring seven principal parts of which few can be easily derived from the infinitive. For some verbs a few of their principal parts are identical with one another.
Paradigm for most irregular verbs (7 principal parts)
Indicative
Subjunctive
Conditional
Imperative
Present
Simple past
Imperfect
Future
Present
Imperfect
Present
Present
je
1S+s
PAST+s
1P+ais
FUT+ai
3P+e
PAST+sse
FUT+ais
tu
FUT+as
3P+es
PAST+sses
(same as pres. indic. 3rd. sg. if ends with vowel, else 2nd. sg.)
il/elle
1S+t1
PAST+t
1P+ait
FUT+a
3P+e
PAST+ˆt
FUT+ait
nous
1P+ons
PAST+ˆmes
1P+ions
FUT+ons
1P+ions
PAST+ssions
FUT+ions
(same as pres. indic. 1st pl.)
vous
1P+ez
PAST+ˆtes
1P+iez
FUT+ez
1P+iez
PAST+ssiez
FUT+iez
(same as pres. indic. 2nd pl.)
ils/elles
3P+ent
PAST+rent
1P+aient
FUT+ont
3P+ent
PAST+ssent
FUT+aient
1 The -t is regularly dropped when directly following a d or t (e.g. il vend "he sells", not *il vendt).
Example with plaire
" Plaire (to please [someone]) and conjugations with 7 principal parts
Indicative
Subjunctive
Conditional
Imperative
Present
Simple past
Imperfect
Future
Present Perfect
Present
Imperfect
Present
Present
je / j'
plais
plus
plaisais
plairai
ai plu
plaise
plusse
plairais
tu
plairas
as plu
plaises
plusses
plais
il/elle
plaît
plut
plaisait
plaira
a plu
plaise
plût
plairait
nous
plaisons
plûmes
plaisions
plairons
avons plu
plaisions
plussions
plairions
plaisons
vous
plaisez
plûtes
plaisiez
plairez
avez plu
plaisiez
plussiez
plairiez
plaisez
ils/elles
plaisent
plurent
plaisaient
plairont
ont plu
plaisent
plussent
plairaient
Verbs with 11 principal parts
A few highly irregular verbs require 11 principal parts to conjugate them fully. It includes all of the seven principal parts as well as a subjunctive form and different present participle forms, imperative forms and present-participle forms.
Fully irregular verbs
The verbs être, avoir and aller are so irregular they require even more than 11 principal parts.
Scottish Gaelic
In Scottish Gaelic there are two principal parts for the regular verb: the imperative and the verbal noun, for example pòg – pògadh 'to kiss'. All finite forms can be deduced from the imperative pòg ('kiss!'), all non-finite forms from the verbal noun pògadh ('kissing'). The ten irregular verbs can, with only two or three small aberrations (unexpected lenition), be deduced from four principal parts.
Ganda
The principal parts of a Ganda verb are the imperative (identical to the verb stem), the first person singular of the present tense and the modified stem. For example, the verb okwogera 'to speak' has the principal parts yogera – njogera – yogedde.
In theory the second principal part can be derived from the first, but in practice this is so complicated that it is usually memorised as a separate principal part.
^ abcdRi-verbs are written with an e in the second principal part according to the Icelandic Ministry of Education even though it is pronounced as if it were written with an é.