escalar
to climb
scale
to climb up something steep and difficult
+
-ar
infinitive verb ending
Escalar means to climb and can be thought of as scale0 (as in to climb up something steep0) + -ar1 (infinitive verb ending1).
verb
  1. to climb
    To climb or ascend, especially a steep or difficult surface
    Los alpinistas planean escalar la montaña más alta. // The mountaineers plan to climb the highest mountain.