Cair

Cair means to fall — physically (a glass falls off the table), figuratively (prices fall, night falls), and idiomatically in a cluster of expressions every Brazilian uses daily. It is an -ir verb, but not a regular one: the stem ends in a vowel (ca-), so when an ending also begins with a vowel you get a hiatus — two vowels in separate syllables — and Portuguese marks the stressed i of that hiatus with an acute accent: caí, caímos, caíram, caía. Getting these accents right is the whole difficulty of this verb. Miss one and you have a spelling error; in caí (I fell) versus cai (he falls), the accent is the only thing distinguishing two different forms.

Core meaning: to fall

Note in the last example that caem (they fall) is written without an accent — the stress there falls on the a, not the i, so no hiatus accent is needed. Compare the third-person singular cai (he/she/it falls), also unaccented, with the first-person preterite caí (I fell), which is accented. This minimal pair trips up nearly every learner.

The í-accent forms (read this twice)

The accent appears exactly where the i carries the stress in a hiatus with the preceding a:

• Pretérito perfeito: caí (I fell), caímos (we fell), caíram (they fell)
• Pretérito imperfeito: caía, caías, caía, caíamos, caíam
• Particípio: caído

It does not appear where the a is stressed: present caio, cai, caem; future cairei, cairá; gerúndio caindo.

Indicative tenses

Presente do indicativo

Note caio with no accent (the i is unstressed there, gliding into o), but caímos with the accent (the i is stressed). The present nós form caímos is spelled identically to the preterite caímos — context disambiguates.

Pretérito perfeito

Accents on caí, caíste, caímos, caíram — but caiu (he/she fell) takes no accent. The hiatus-accent rule only applies to a stressed i that stands alone (or with a final s) in its syllable: ca-í, ca-í-mos. In caiu, the iu is read as a falling diphthong in a single syllable — ca-iu, not ca-í-u — so there is no hiatus to mark and no accent. This is exactly why monosyllables like cai, sai, pai are never accented either. Memorize it directly: caiu, never "caíu".

Pretérito imperfeito

Every form here carries the accent, because the i is stressed throughout.

Futuro do presente

No hiatus accent here — the stress sits on the ending (-ei, -á, -ão), so the i of the stem is unstressed.

Futuro do pretérito (conditional)

Subjunctive

Presente do subjuntivo

Built from the present eu stem caio → caia. No accent: the stress is on the a. Be careful not to confuse the subjunctive caia (that he fall) with the imperfect indicative caía (he used to fall) — the accent is doing real grammatical work here.

Imperfeito do subjuntivo

All accented — built off the preterite stem caí-.

Futuro do subjuntivo

The tu and eles forms (caíres, caírem) carry the accent because the i is stressed; the bare cair and cairmos do not.

Imperative

The imperative of cair is rarely a literal command ("fall!"). It shows up mostly in the slang cai fora! ("get lost! / clear out!") — see the idioms below.

Non-finite forms

Note caindo (no accent — stress on the a) but caído (accent — i stressed in hiatus). That contrast inside the same verb's non-finite forms is the cleanest illustration of the whole rule.

Idioms with cair

Brazilian Portuguese leans heavily on cair for figurative meaning. These are everyday, not bookish.

cair em — to fall for / fall into (a trap, a scam, sleep):

cair bem / cair mal — to suit / look good, or to sit well (food, a gift, a comment):

cair fora — (slang, informal) to clear out, bail, get out of somewhere:

cair a ficha — (informal) for something to finally click / dawn on you. Literally "the token drops," from old coin-operated payphones:

Source-language note for English speakers

English splits "fall" across many verbs depending on register and context — fall, drop, collapse, tumble, plummet — and uses "fall for" and "fall into" as phrasal verbs. Portuguese concentrates most of this on cair plus a preposition, which is convenient, but the trap is the preposition: it's cair em (fall for/into), cair de (fall off/from), and cair sobre (fall upon). There is no preposition-free "fall something" — cair is intransitive. To express "to drop something" (transitively), Brazilians use derrubar (Eu derrubei o copo = I dropped the glass), not cair.

Common Mistakes

Key Takeaways

• Accent the stressed i in hiatus: caí, caíste, caímos, caíram, caía(s), caíamos, caíam, caíssemos, caído, caíres, caírem.
• Do not accent: caio, cai, caem, caiu, caindo, cairei, caia (subjunctive).
• The minimal pairs cai / caí and caía / caia are distinguished only by the accent — the accent carries meaning.
• Cair is intransitive; "to drop (something)" is derrubar.
• Master the idioms cair em, cair bem/mal, cair fora, cair a ficha — they are everywhere in spoken Brazilian Portuguese.