c. 1300, "amorous playing, sport," later "piece of fun or entertainment" (c. 1500), "thing of little value, trifle" (1520s), and "thing for a child to play with" (1580s). Of uncertain origin, and there may be more than one word here. Compare Middle Dutch toy, Dutch tuig "tools, apparatus; stuff, trash," in speeltuig "play-toy, plaything;" German Zeug "stuff, matter, tools," Spielzeug "plaything, toy;" Danish tøj, Swedish tyg "stuff, gear." Applied as an adjective to things of diminutive size, especially dogs, from 1806. Toy-boy is from 1981.
"deal carelessly (with), trifle," 1520s, from toy (n.) in its older sense.
If he be merie and toy with any,
His wife will frowne, and words geve manye.
["Song of the Bachelor's Life," 16c.]
Related: Toyed; toying.