rebus n.

a puzzle or riddle consisting of words or phrases represented by pictures of objects whose names resemble in sound the words or phrases intended, c. 1600, apparently from Latin rebus (and meaning literally "by means of objects"), ablative plural of res "thing, object" (see re). According to French sources (Gilles Ménage, "Les origines de la langue françoise," 1650), principally from the phrase de rebus quæ geruntur "of things which are going on," in reference to the satirical pieces composed by Picardy clerks at carnivals, subtle satires of current events using pictures to suggest words, phrases or things. Or this use of the Latin word might be from the representations being non verbis sed rebus "not by words, but by things."