- The definition of gizmo is slang for a gadget, especially an unnecessary one or one whose user can't remember its name.
An overly fancy corkscrew opener that does way more than you would ever need it to do is an example of a gizmo.
gizmo definition by Webster's New World
Origin: ; from uncertain or unknown; perhaps Spanish gisma, obsolete or dialect, dialectal variant, variety of chisme, trifle, jigger, ultimately ; from Classical Latin cimex, a bug
gizmo definition by American Heritage Dictionary
also gis·monoun pl. giz·mos also gis·mos
Origin: Origin unknown.