Irregular Verbs:
“esse” and “posse”
Present System
Magister Henderson
Latin II
About “sum, esse” (to be)
• The verb sum, esse is a linking verb, meaning
it takes a predicate nominative rather than a
direct object.
• It is irregular in all three forms of the present
system (present, imperfect, and future).
Present Tense
Singular
First Person
sum
Second Person
es
Third Person
est
= I am
Plural
sumus
= we are
= you are
estis
= you are
= he / she / it is
sunt
= they are
Imperfect and Future of “esse”
Imperfect Tense
Singular
First Person
eram
= I was
Second Person
erās
Third Person
erat
Future Tense
Plural
erāmus
= we were
= you were
erātis
= you were
= he / she/ it was
erant
= they were
Singular
First Person
erō
= I will be
Second Person
eris
Third Person
erit
Plural
erimus
= we will be
= you will be
eritis
= you will be
= he will be
erunt
= they will be
About “possum, posse” (to be able)
• Compound form of potis and sum, esse.
• The prefix “pot-” is used for forms of esse that
begin with “s” (sum, sumus, and sunt).
• For forms that begin with “e” (es, est, and
estis), the prefix assimilates to “pos-”.
Present Tense
Singular
First Person
possum
Second Person
potes
Third Person
potest
= I can
Plural
possumus
= we can
= you can
potestis
= you can
= he / she / it can
possunt
= they can
Imperfect and Future of “posse”
All the imperfect and future tense forms of posse use
“pot-” since all forms of esse in the imperfect and future
tenses begin with the letter “e”.
Imperfect Tense
First Person
Singular
poteram = I could
Plural
poterāmus
= we could
Second Person
poterās
= you could
poterātis
= you could
Third Person
poterat
= he / she / it could
poterant
= they could
Future Tense
Singular
Plural
First Person
poterō
= I will be able
potermus
= we will be able
Second Person
poteris
= you will be able
poteritis
= you will be able
Third Person
poterit
= he will be able
poterunt
= they will be able
Translating the verb “posse”
• To translate possum, posse use either the defect
verb “can” or the phrase “be able (to)”.
• Defective verbs are verbs that are missing forms.
For the missing forms you will need to use some
form of “be able (to)”.
Form
Latin
Verb Translation
Phrase Translation
Infinitive
posse
n/a
= to be able (to)
Present tense
possum
= I can
= I am able (to)
Imperfect Tense
poteram
= I could
= I was able (to)
Future Tense
poterō
n/a
= I will be able (to)