Irregular Verbs

Some very common Latin verbs don't belong to any particular conjugation: they change their endings in unpredictable ways.

sum esse, be

The verb sum esse, be is the most common irregular verb in Latin. It has several compounds, including possum posse, can, be able.

sum esse (be) possum posse (can, be able)
first person singular sum I am possum I can
second person singular es you s. are potes you s. can
third person singular est he/she/it is potest he/she/it can
first person plural sumus we are possumus we can
second person plural estis you pl. are potestis you pl. can
third person plural sunt they are possunt they can
infinitive esse to be posse to be able
imperative singular es, esto be! s. — —
imperative plural este, estote be! pl. — —

The compounds of sum esse include:

adsum adesse
be present

eo ire, go

The verb eo ire, go is also irregular. It has a number of compounds.

eo ire (go)
first person singular eo I go
second person singular is you s. go
third person singular it he/she/it goes
first person plural imus we go
second person plural itis you pl. go
third person plural eunt they go
infinitive ire to go
imperative singular i go! s.
imperative plural ite go! pl.

The compounds of eo ire include:

abeo abire
go away, depart
adeo adire
go towards, approach
ineo inire
go in, enter
redeo redire
go back, return

volo velle, want and nolo nolle, not want, refuse

The verb volo velle, want has a negative version nolo nolle, not want, refuse.

volo velle (want) nolo nolle (not want, refuse)
first person singular volo I want nolo I don't want
second person singular vis you s. want non vis you s. don't want
third person singular vult he/she/it wants non vult he/she/it doesn't want
first person plural volumus we want nolumus we don't want
second person plural vultis you pl. want non vultis you pl. don't want
third person plural volunt they want nolunt they don't want
infinitive velle to want nolle to not want

fero ferre, carry, bear, bring

The verb fero ferre, carry, bear, bring is basically a third conjugation verb with a few irregular forms.

fero ferre (carry, bear, bring)
first person singular fero I carry
second person singular fers you s. carry
third person singular fert he/she/it carries
first person plural ferimus we carry
second person plural fertis you pl. carry
third person plural ferunt they carry
infinitive ferre to carry
imperative singular fer carry! s.
imperative plural ferte carry! pl.