late 14c., preserven, "keep safe or free from harm," also "act so as to insure that something does not occur," from Anglo-French preservare, Old French preserver, Medieval Latin preservare "keep, preserve," all from Late Latin praeservare "guard beforehand," from Latin prae "before" (see pre-) + servare "to keep safe" (from PIE root *ser- (1) "to protect").
From early 15c. as "maintain, keep in a certain quality, state or condition." Of fruit, etc., "prevent from spoiling by use of preservative substances," 1570s; of organic bodies, "keep in existence or alive," from 1610s. Related: Preserved; preserver; preserving.
"fruit preserved with sugar," c. 1600, from preserve (v.). Earlier it meant "a preservative" (1550s). Sense of "protected place for animals or plants" (a sense more properly belonging to conserve) is from 1807. The verb preserve in the sense of "maintain and reserve for special use in hunting or fishing" is from 1610s.
early 15c., preservacioun "protection from disease," from Old French preservacion (13c.), from Medieval Latin preservationem (nominative preservatio), noun of action from past-participle stem of preservare "to guard beforehand" (see preserve (v.)). General sense of "protection, act of keeping safe or sound" is from mid-15c.
late 14c., preservatif, "tending to keep safe, sound, or free from harm," from Old French preservatif and directly from Medieval Latin praeservativus, from stem of Late Latin praeservare "guard beforehand" (see preserve (v.)).
The noun is from early 15c., "a preservative medication; substance that preserves corpses," also generally "anything that preserves or maintains." The sense of "chemical added to foods to keep them from rotting" is from 1875.
It is the hypothetical source of/evidence for its existence is provided by: Avestan haurvaiti "to guard;" Latin servare "to guard, keep, watch;" Old Church Slavonic xraniti "to guard, protect;" Old High German gi-sarwi "armor, equipment," Old English searu "art, skill; wile, deceit."