Similar words
quizás
quizás is the everyday word for "perhaps, maybe"; acaso is more literary or formal, and can also be used rhetorically, as in "¿Acaso no lo sabías?"
Similar in other languages
Portuguese
quiçá
quiçá is the Portuguese word for the same thing — both mean "perhaps."
Practice
1 What does acaso mean?
perhaps
2 Fill the gap: ¿___ no lo sabías?
Full sentence: ¿Acaso no lo sabías? (Didn't you know?)
3 Which fingerprint chart matches acaso?
acaso: neutral register, common frequency, general domain, neutral connotation.