Present Indicative of Sum

Sum is Latin’s basic verb “be.” Its present indicative forms—sum, es, est, sumus, estis, sunt—express identity, description, location, and existence. They also participate in constructions that English phrases with “have,” although deeper treatment of those uses belongs to later pages.

The paradigm is irregular because it continues more than one inherited stem shape. There is no productive rule that derives every form by attaching the ordinary endings to one visible stem. The good news is that the six forms are short, extremely frequent, and internally patterned enough to memorize as two rows.

Principal parts and the present paradigm

The conventional principal parts are sum, esse, fuī, futūrus “be.” Sum has no ordinary supine; futūrus is its future active participle. The present infinitive esse and the forms es, est, estis reveal an es- shape, while sum, sumus, and sunt reveal an s- shape with different vowels.

The endings -t, -mus, -tis, and -nt still help identify person and number, but forms such as sum and es cannot be generated from the regular conjugation templates. Learn the full sequence aloud: sum, es, est; sumus, estis, sunt.

These are ordinary, unmarked Classical forms. The pronouns “I,” “we,” and “you all” are contained in the verbal morphology; an explicit ego, nōs, or vōs would add contrast or emphasis.

Linking a subject to a predicate

As a copula, sum links the subject to a noun or adjective that identifies or describes it. The predicate noun is nominative because it refers to the same entity as the nominative subject; it is not a direct object.

In frāter medicus est, both frāter and medicus are masculine singular nominative. In Lūcia et Cornēlia fessae sunt, the adjective is feminine plural nominative and sunt is plural. The verb agrees with the subject; a predicate adjective also agrees with that subject in gender, number, and case.

Latin has no indefinite article corresponding to English “a.” Medicus est means “he is a doctor,” not merely “he is doctor.” Adding an invented article would distort the noun phrase rather than clarify it.

Location and presence

With a place expression, sum says where someone or something is. The place phrase has whatever case its own construction requires—often in plus ablative for location—while the entity located remains nominative.

English uses the same verb “be,” and here the match is close. Still, the cases matter: plural nominative clāvēs requires plural sunt, while mēnsā and arcā are ablative after locative in. Latin word order can place the location first without changing the grammar: in mēnsā clāvēs sunt.

The compounds of sum refine location and relation: adsum “be present,” absum “be absent,” īnsum “be in,” and others. They retain recognizable forms of sum but receive full treatment in Sum and Its Compounds.

Existence: “there is” and “there are”

Latin often places est or sunt before an indefinite subject to introduce it. English translates this construction with dummy “there,” but Latin has no equivalent dummy word. The real Latin subject is nominative and controls the number of the verb.

The contrast is grammatical: singular taberna goes with est; plural librī goes with sunt. It would be wrong to treat est as an invariant translation of English “there is/are.”

Basic possession with a dative

Latin can express possession as “there is X to Y.” The possessed thing is nominative and controls est/sunt; the possessor is dative. This construction is ordinary Classical Latin, not especially (formal) or (literary).

The English subject becomes a Latin dative: “I” → mihi, “Lucius” → Lūciō. The Latin nominative instead names what is possessed: singular hortus takes est, plural frātrēs takes sunt. This is a structural difference, not a decorative alternative word order. See Possession with Sum and the Dative for contrasts with habeō and more complex examples.

Tense, mood, and voice

All six forms on this page are present indicative. They present identity, state, location, or existence as actual in the current discourse. Unlike a regular transitive verb, sum has no passive paradigm: “be” does not assign an active agent and passive patient in the way laudō/laudor does. Forms such as **suntur are impossible.

English progressive “is being” does not usually correspond to a special form of sum. A temporary property still uses the ordinary present:

The adverb hodiē makes the description temporary. Latin does not need a separate copula to contrast permanent identity with temporary state.

Classical Latin very commonly omits the present copula when the relation is clear; this is not confined to poetry. The omission is especially easy in proverbs, paired descriptions, and other compact expressions. Beginners should recognize such ellipsis but should not delete the copula mechanically from every sentence. Explicit vīta brevis est transparently means “life is short,” while compressed vīta brevis relies on context.

Parsing and production diagnostics

When you meet estis, identify -tis as second-person plural and recognize the irregular es- base. The parse is present indicative, second-person plural: “you all are.” In an unmacronized text it can be confused with ēstis, an alternative second-person plural of edō “eat”; vowel quantity and context distinguish the two.

To produce “the girls are ready,” choose third-person plural sunt, make puellae nominative plural, and make the predicate adjective agree: puellae parātae sunt. To produce “there is a road,” choose singular est because nominative via is singular: est via.

Common Mistakes

1. Making the predicate noun accusative

2. Treating est as invariant in existential clauses

3. Copying English possession word for word

4. Inventing a passive form

5. Adding an English-style article

Key Takeaways

Memorize sum, es, est; sumus, estis, sunt as one irregular present indicative paradigm. Use it with nominative predicate nouns and agreeing adjectives, with place expressions, and existentially with a nominative subject that determines singular est or plural sunt. In the dative-possession construction, the possessor is dative and the possessed thing is the grammatical subject. Parse those Latin relationships before reaching for an English form of “be” or “have.”