mother tongue
native language , także: native tongue

People say I should learn my native tongue, as well.

No one here had seemed to speak his native tongue.

I had no doubt that his native tongue was English.

I might as well have listened to their native tongue.

At first it seems the girls are singing in their native tongue.

The baby answered him in all, and no one could have told which was his native tongue!

"Would he have something to teach his own native tongue in there?"

She'd never heard one quite like it, and she wondered what the other's native tongue was.

Some he stood over and spoke to, quietly, in their native tongue.

He did not speak at all to them in his native tongue, Hebrew.