Tagalog is defined as a dialect of a group of people who live in the Manila area of the Philippine Islands.(noun)
See Tagalog in Webster's New World College Dictionary
See Tagalog in American Heritage Dictionary 4
noun pl. Tagalog Tagalog or Ta·ga·logs
Origin: Perhaps Tagalog, river people
Origin: : taga-, native of
Origin: + ilog, river.