Origin and history of useful

c. 1300, "act of employing (something) fact of being used or employed;" also "individual habit or practice; manner of living, way of using;" from Anglo-French and Old French us, hus "custom, practice, usage." This is from Latin usus "use, custom, practice, employment, skill, habit," from past-participle stem of uti "make use of, profit by, take advantage of" (see use (v.)).

By late 14c. in English as "purpose, function; benefit; consumption; established custom among a set of people." To be of no use "be worthless" is from late 14c.

word-forming element attached to nouns (and in modern English to verb stems) and meaning "full of, having, characterized by," also "amount or volume contained" (handful, bellyful); from Old English -full, -ful, which is full (adj.) become a suffix by being coalesced with a preceding noun, but originally a separate word. Cognate with German -voll, Old Norse -fullr, Danish -fuld. Most English -ful adjectives at one time or another had both passive ("full of x") and active ("causing x; full of occasion for x") senses.

It is rare in Old English and Middle English, where full was much more commonly attached at the head of a word (for example Old English fulbrecan "to violate," fulslean "to kill outright," fulripod "mature;" Middle English had ful-comen "attain (a state), realize (a truth)," ful-lasting "durability," ful-thriven "complete, perfect," etc.).