What is the meaning of idiomatic expression mother tongue?

"Mother tongue" is an idiomatic expression that refers to the first language a person learns to speak. It's the language a person is most comfortable and fluent in, usually learned from their parents or caregivers during childhood.

Here's a breakdown of the meaning:

* Mother: Represents the primary source of language learning, often the mother figure.

* Tongue: Refers to the language itself.

The phrase implies a close and natural connection between the individual and the language, akin to the bond between a mother and child.

Examples:

* "My mother tongue is Spanish, but I'm fluent in English as well."

* "Learning a new language can be challenging, especially when trying to master a second tongue after your mother tongue."

It's important to note that the term "mother tongue" doesn't necessarily imply the person's biological mother or even a female caregiver. It simply refers to the language learned first and most deeply.