cliffn.[AS. clif, cloef; akin to OS. klif, D. klif, klip, Icel. klif, Dan. & G. klippe, Sw. klippa; perh. orig. a climbing place. See Climb.] A high, steep rock; a precipice.()Cliff swallow (Zol.), a North American swallow (Petrochelidon lunifrons), which builds its nest against cliffs; the eaves swallow.()n. (Mus.) See Clef.()