noun

• (countable, also figuratively) A fact or statement used to support a proposition; a reason.
  "There is no greater, at leaſt no more palpable and convincing Argument of the Exiſtence of a Deity than the admirable Art and Wiſdom that diſcovers itſelf in the make and conſtitution, the order and diſpoſition, the ends and uſes of all the parts and members of this ſtately fabrick of Heaven and Earth."
• (countable, also figuratively) A fact or statement used to support a proposition; a reason.
  "Consider the argument: / 15) I am hungry; therefore I am hungry. / Intuitively this should count as valid. But suppose we thought of the components of arguments as sentences, and suppose we imagine the context shifting between the utterance of the premise and the utterance of the conclusion. Suppose you are hungry and utter the premise, and I am not hungry and utter the conclusion. Then we would have a true premise and a false conclusion, so the argument would not be valid. Clearly we need to avoid such problems, and introducing the notion of a proposition, in the style of this section, is one way of doing so."
• (countable) A process of reasoning; argumentation.
  "Indeed, I cannot commend my life; for I am conſcious to my ſelf of many failings: therein, I know alſo that a man by his converſation, may ſoon overthrow what by argument or perſwaſion he doth labour to faſten upon others for their good: […]"
• (countable) An abstract or summary of the content of a literary work such as a book, a poem or a major section such as a chapter, included in the work before the content itself; (figuratively) the contents themselves.
  "If I would broach the veſſels of my loue, / And try the argument of hearts, by borrowing, / Men, and mens fortunes, could I frankely vſe / As I can bid thee ſpeake."

verb

• (intransitive, obsolete, now nonstandard, non-native speakers' English) To put forward as an argument; to argue.
  "[I]t is moſt certaine, that after Herodotus and other auncient writers, it is ſafer to call theſe [elephants' tusks] teeth, then hornes; and I will breefly ſet downe the reaſons of Philoſtratus, that will haue them to be teeth, and afterward of Grapaldus [i.e., Francesco Mario Grapaldi], Aelianus, and Pauſanias, that would make them horns, and ſo leaue the reader to conſider whether opinion he thinketh moſt agreeable to truth. […] Thus they argument for the horns of Elephants."
• (intransitive, obsolete) To adduce evidence, to provide proof.
  "Albeit that it apperteneth to the apoſtolis, be the puiſtoun of God to tak ordour in all materis off debait cõcernyng ye faith, & ſpecialie to iterprete ye ſcripturis, as yat quhilkis had yͤ ſpreit of god, & wer yͤ trew kirk: It argumẽtis [argumentis] not yat vtheris, quha hes ꝯuenit [conuenit] ſenſyne in generale ꝯſales [consales] had the ſpreit of GOD, or wer the trew kirk: […]"