Where does the word “Slyboots” come from and What does Slyboots mean?

Although slyboots has the meaning of “a crafty or cunning person,” it is closely related to footpad, “a thief”; gumshoe, “a detective”; pussyfoot, “a prying, nosy person”; also to the German Leisetreter (light treader), “a sneak, spy”; and the French pied plat (flat foot), “a sneak, knave.”

All of these carry the common connotation of a person who moves with quiet or stealth, and always these movements are contrary to the well-being or comfort of the one applying the term (even the gumshoe is so-called only by the one who is attempting some clandestine act).

The American flatfoot, of course, is quite different from the French, being a policeman, specifically, one who has walked on patrol for so long that his arches are presumed to have fallen and, in fact, he has acquired flat feet.