nicky-tam (n.)

also nicky tam, "garter worn over trousers," 1911, Scottish, from a shortened, colloquial form of knickers + Scottish & northern English dialect taum, from Old Norse taumr "cord, rein, line," cognate with Old English team, the root sense of which appears to be "that which draws" (see team (n.)). Originally a string tied by Scottish farmers around rolled-up trousers to keep the legs of them out of the dirt.