English

father tongue

From father + tongue (“language”), modelled after mother tongue.

A compound of father + tongue ‘language’

Proto-Indo-European *ph₂tḗr

Proto-Germanic *fadēr

Proto-West Germanic *fader

Old English fæder

Middle English fader ‘a father’

Proto-Indo-European *dn̥ǵʰwéh₂s

Proto-Germanic *tungǭ

Proto-West Germanic *tungā

Old English tunge

Middle English tongue

Today it means

noun A separate language for expressing ideas, as opposed to the vernacular (mother tongue) which is employed for everyday speech.

Language periods are conventional ranges, not dates for this word.

Etymograph / father tongue