Sum, Esse, Fui: To be

The Latin word sum is perhaps among the best known of all the Latin verbs and it is among the hardest to learn. Sum is the present indicative tense of the verb esse, meaning "to be."

As with many other living and dead languages, esse is one of the oldest verb forms in Latin, one of the most frequently used of the verbs, and one of the most irregular verbs in Latin and related languages.

It is also often contracted in casual use (such as in English I'm, that's, they're, he's), so that the verb is almost invisible to the listener.

Present System (indicative) Perfect System (indicative)

Present System (subjunctive) Perfect System (subjunctive)

Sum, esse has a number of compounds in addition to possum (the most common). These compounds all follow the same patterns as outlined above, simply changing the prefix.