noun
(uncountable, archaic) Verbal exchange, conversation.
(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).
(Internet, uncountable) Lengthy, often heated debate over controversial subject matter, particularly within fandom and activist spaces. Sometimes rendered as a proper noun with the definite article (i.e. "the Discourse").
(obsolete) Dealing; transaction.
verb
(intransitive) To engage in discussion or conversation; to converse.
(intransitive) To write or speak formally and at length.
(obsolete, transitive) To debate.
To exercise reason; to employ the mind in judging and inferring; to reason.
(obsolete, transitive) To produce or emit (musical sounds).