Synonyms for Could:

n.

perhaps, maybe, it's just a thought, what if, I thought (that), how about...?, Why-not. Befell, Awoken, Arose, awoke, bade, Begat, Bestrode, ate, Became, Began. darn, what's that supposed to mean?, for heaven's sake/sakes, what's the big idea?, for pity's sake, brother, give me strength, give me a break, for crying out loud. may, must, can, used to, should, ought, Cannot, shall. could (noun)
might.

Other synonyms:

should, ought, Cannot, shall. used to, must, maybe. may. can. Other relevant words:
may, should, must, Cannot, ought, can, shall, perhaps, maybe.

Usage examples for could

  1. But what could it be? – Amusement Only by Richard Marsh
  2. She could see now that she did. – Mary Marie by Eleanor H. Porter
  3. Might, could would, or should we not love? – The Grammar of English Grammars by Goold Brown