mid-13c., "to merit, be worthy of for qualities or actions," from Old French deservir (Modern French desservir) "deserve, be worthy of, earn, merit" and directly from Latin deservire "serve well, serve zealously," from de- "completely" (see de-) + servire "to serve" (see serve (v.)). The classical Latin sense evolved to "be entitled to because of good service" (a sense found in Late Latin), then in French "be worthy of."
