fit

{{11}}fit (adj.) "suited to the circumstances, proper," mid-15c., of unknown origin, perhaps from M.E. noun fit "an adversary of equal power" (mid-13c.), which is perhaps connected to FIT (Cf. fit) (n.¹). Survival of the fittest (1867) coined by H. Spencer.

{{12}}fit (n.¹) 1823, "the fitting of one thing to another," later (1831) "the way something fits." Originally "an adversary of equal power" (mid-13c.), obscure, possibly from O.E. fitt "a conflict, a struggle" (see FIT (Cf. fit) (n.²)).

{{12}}fit (n.²) "paroxysm, sudden attack" (as of anger), 1540s, probably via M.E. sense of "painful, exciting experience" (early 14c.), from O.E. fitt "conflict, struggle," of uncertain origin, with no clear cognates outside English. Perhaps ultimately cognate with FIT (Cf. fit) (n.¹) on notion of "to meet." Phrase by fits and starts first attested 1610s.

{{13}}fit (n.³) “part of a poem,” O.E. fitt, of unknown origin.

{{14}}fit (v.) "be suitable," probably from early 15c.; “to be the right shape,” 1580s, from FIT (Cf. fit) (adj.). Related: Fitted; fitting. Fitted sheets is attested from 1963.