conditional mood
Definition - The form a verb takes to refer to events that will happen if something else it true.

Example -

(1) If he shows up, I'm leaving.
(2) If you give me $5, I'll sell you this dog.

Etymology -
The word derives via Old French from the Latin condicionem, agreement or situation (from com-, together + dicere, to speak).

Oxford English Dictionary -
Its first citation is from 1530:
"Modes they have vii, the indicative … the subjunctive …the potenciall … the imperatyve … the optative … the condicional, the infinitive.… [Ibid.] The condicional mode whiche they use whan they expresse condicion if a dede be to be done, as sy je parle."
(Jehan Palsgrave, Lesclarcissement de la langue françoyse, 84)

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