What does "ladder" mean?

Ladder: 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 under Fish. -- Ladder beetle (Zoöl.), an American leaf beetle (Chrysomela scalaris). The elytra are silvery white, striped and spotted with green; the under wings are rose-colored. It feeds upon the linden tree. -- Ladder handle, an iron rail at the side of a vertical fixed ladder, to grasp with the hand in climbing. -- Ladder shell (Zoöl.), a spiral marine shell of the genus Scalaria. See Scalaria.