(grammar) A word (pronoun, pronominal adjective, or adverb) implying interrogation, or used for asking a question: why, who, when, etc. / (typography, archaic) Synonym of question mark ⟨?⟩.

(with the) An attack of uncontrolled giggling.

Excessively pensive.

Any sponge of the family Pseudoceratinidae