1. A frame usually portable, of wood, metal, or rope, for ascent and descent, consisting of two side pieces to which are fastened cross strips or rounds forming steps. Some the engines play, And some, more bold, mount ladders to the fire. (Dryden)
2. That which resembles a ladder in form or use; hence, that by means of which one attains to eminence. Lowliness is young ambition's ladder. (Shak) fish ladder. See fish. Ladder beetle, a spiral marine shell of the genus scalaria. See scalaria.