1Now usually in plural Either of two North American migratory sandpipers, Totanus flavipes (more fully "lesser yellowlegs") and T. melanoleuca (more fully "greater yellowlegs"), having long, thin, dark beaks, long yellow legs, and a grey-brown body with dark markings and pale underparts. Occasionally: †a yellow-legged domestic fowl (obsolete).
2US informal, historical A cavalryman in the U.S. army; especially one in the Confederate army. Also in plural in same sense.
3North American informal, historical A member of the Royal Canadian Mounted Police. Also in plural in same sense.
Late 18th century. From yellow + leg.