How to Conjugate the Irregular Latin Verb Sum ("To Be")

The Latin word sum is perhaps among the best-known Latin verbs and 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 verbs, and one of the most irregular verbs in Latin and related languages. It's also often contracted in casual use (such as in English I'm, that's, they're, he's), so the verb is almost invisible to the listener.

Etymology

The progenitor form of "to be" is in the Proto-Indo-European (PIE) language, the parent language of Latin, Greek, Sanskrit, Iranian, Germanic, and indeed most of the languages spoken in all of Europe, India, and Iran. Each of the PIE languages has a form of "to be," perhaps because it's so eminently useful: sometimes "to be" can have an existential significance ("To be or not to be," "I think therefore I am"), but also retains its use in everyday language.

In etymological circles, "to be" is the b-root word, and like all of the b-roots, it's probably derived from an ancient PIE root, today reconstructed as *h1és-mi (I am). It's also possible that "to be" in Latin derives from the root word *bhuH- meaning "to grow." Other closely related words to esse are asmi in Sanskrit and ešmi in Hittite.

Conjugating Sum

Irregular Verbs and Compounds

There are several other Latin irregular verbs and compound verbs formed from sum.

Sources

• Moreland, Floyd L., and Fleischer, Rita M. "Latin: An Intensive Course." Berkeley: University of California Press, 1977.
• Traupman, John C. "The Bantam New College Latin & English Dictionary." Third Edition. New York: Bantam Dell, 2007.