tongue (n.) Look up tongue at Dictionary.com
Old English tunge "organ of speech, speech, language," from Proto-Germanic *tungon (cf. Old Saxon and Old Norse tunga, Old Frisian tunge, Middle Dutch tonghe, Dutch tong, Old High German zunga, German Zunge, Gothic tuggo), from PIE *dnghwa- (cf. Latin lingua "tongue, speech, language," from Old Latin dingua; Old Irish tenge, Welsh tafod, Lithuanian liezuvis, Old Church Slavonic jezyku).

For substitution of -o- for -u-, see come. The spelling of the ending of the word apparently is a 14c. attempt to indicate proper pronunciation, but the result is "neither etymological nor phonetic, and is only in a very small degree historical" [OED]. Meaning "foreign language" is from 1530s. Tongue-tied is first recorded 1520s.
tongue (v.) Look up tongue at Dictionary.com
"to touch with the tongue, lick," 1680s, from tongue (n.). Earlier as a verb it meant "drive out by order or reproach" (late 14c.). Related: Tongued; tonguing.