c. 1200, "action of serving," originally in reference to performing rites or worshipping (God or a pagan god), verbal noun from serve (v.). As "a helping of food" from 1769; earlier "the manner of carving at table" (c. 1400). Serving-board "table for serving food" is from mid-15c.
"that does service (to another)," c. 1300, present-participle adjective from serve (v.).
early 15c., palliatif, "serving to mitigate or alleviate" (a wound, disease, etc.); also "serving to cover, concealing;" from Medieval Latin palliativus "under cloak, covert," from Late Latin palliatus, literally "cloaked," from past participle of Late Latin palliare "cover with a cloak, conceal," from Latin pallium "a cloak" (see pall (n.)). Meaning "serving to extenuate by excuses or favorable representation" is by 1779. As a noun, "that which mitigates or extenuates," by 1724.
"working or acting for reward, serving only for gain," hence "resulting from sordid motives, ready to accept dishonorable gain," 1530s, from mercenary (n.), or in part from Latin mercenarius "hired, paid, serving for pay."