mother tongue

US /ˈmʌð.ər ˌtʌŋ/
UK /ˈmʌð.ər ˌtʌŋ/
"mother tongue" picture
1.

母語, 母国語

the language that a person has grown up speaking from childhood; the native language of a person or a group of people

:
English is my mother tongue, but I also speak French fluently.
英語は私の母語ですが、フランス語も流暢に話せます。
Learning a new language is easier if you have a strong foundation in your mother tongue.
母語にしっかりとした基礎があれば、新しい言語を学ぶのはより簡単です。