Old English helpan "to help, support, succor; benefit, do good to; cure, amend" (transitive, class III strong verb; past tense healp, past participle holpen), from Proto-Germanic *helpanan (source also of Old Norse hjalpa, Old Frisian helpa, Middle Dutch and Dutch helpen, Old High German helfan, German helfen), a word of uncertain origin. Perhaps it is cognate with Lithuanian šelpiu, šelpti "to support, help."

The intransitive sense of "afford aid or assistance," is attested from early 13c. The word is recorded as a cry of distress from late 14c. The sense of "serve someone with food at table" (1680s) is translated from French servir "to help, stead, avail," and led to helping (n.) "portion of food."

Help yourself as an invitation, in reference to food, etc., is from 1894. Related: Helped (c. 1300). The Middle English past participle holpen survives in biblical and U.S. dialectal use.

early 15c., "readiness" (in phrase in prompte), from Latin promptus (see prompt (v.)). Meaning "hint, information suggested, act of prompting" is from 1590s. The computer sense of "message given by a computer requiring or helping the user to respond" is by 1977.

late 13c., "a bite, mouthful; small piece of food, fragment," from Old French morsel (Modern French morceau) "small bite, portion, helping," diminutive of mors "a bite," from Latin morsum, neuter of morsus  "biting, a bite," past participle of mordēre "to bite," which is perhaps from an extended form of PIE root *mer- "to rub away, harm."

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.

c. 1600, "articles below the first quality," plural of second (n.) in the sense of "that which is after the first" (fingers, sons, Commandments, etc., early 14c.), from second (adj.). First attested in this sense in a Shakespeare sonnet. Meaning "second helping of food at a meal" is recorded from 1792.