Source : Webster's Revised Unabridged Dictionary (1913)

Westerly \West"er*ly\, a.
   Of or pertaining to the west; toward the west; coming from
   the west; western.

Westerly \West"er*ly\, adv.
   Toward the west; westward.

Source : WordNet®

westerly
     adj 1: lying in or toward the west [syn: {western}]
     2: of wind; from the west [syn: {western}]
     3: moving toward the west; "westbound pioneers" [syn: {westbound},
         {westward}]
     n : the west-to-east winds that occur in the temperate zones of
         the Earth [syn: {prevailing westerly}]
     adv 1: toward the west; "we began to steer away westerly"- Daniel
            Defoe
     2: from the west; "the wind blew westerly" [ant: {easterly}]