(uncountable) Expression in words, either speech or writing.

(countable) A conversation.

(countable) A formal lengthy exposition of some subject, either spoken or written.

(countable) Any rational expression, reason.

(social sciences, countable) An institutionalized way of thinking, a social boundary defining what can be said about a specific topic (after Michel Foucault).

(intransitive) To engage in discussion or conversation; to converse.

(intransitive) To write or speak formally and at length.

To exercise reason; to employ the mind in judging and inferring; to reason.