1942, "Marine and Navy usage for any old thing you can't put a name to" ["Life" magazine, July 30, 1945], of unknown origin, perhaps a made-up word. Compare gadget, thingamajig.
there may be some great new gizmo around the corner that you will want to use
give-and-take
give-away
given
giver
Giza
gizmo
gizzard
glabella
glabrous
glace
glacial