1520s, from wish (n.) + -ful. Related: Wishfully; wishfulness. Wishful thinking is recorded from 1907.
Entries linking to wishful
wish n.
early 14c., "act of wishing," also "what one wishes for," from wish (v.). Cognate with Old Norse osk, Middle Dutch wonsc, Dutch wens, Old High German wunsc, German Wunsch "a wish." Wish fulfillment (1901) translates German wunscherfüllung (Freud, "Die Traumdeutung," 1900).
-ful
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.).