Source : Webster's Revised Unabridged Dictionary (1913)

Tagalog \Ta*ga"log\, n.
   1. (Ethnol.) Any member of a certain tribe which is one of
      the leading and most civilized of those native of the
      Philippine Islands.

   2. The language of the Tagalogs. It belongs to the Malay
      family of languages and is one of the most highly
      developed members of the family.

Source : WordNet®

Tagalog
     n 1: a member of a people native to the Philippines chiefly
          inhabiting central Luzon around and including Manila
     2: language of the Tagalog people on which Filipino is based