late 14c., "done in consequence of or in prosecution of something," from Anglo-French pursuant, from Old French poursuiant, porsivant, present participle of porsuir, porsivre "chase, pursue" (see pursue). Meaning "carrying out; following, according" is from 1690s. As an adverb, "according, agreeably," 1670s. As a noun, "one who seeks, an aspirant," late 14c.
c. 1400, "act of eating; act of regulating food intake according to regimen," verbal noun from diet (v.).