expression
not only ... (but also); not merely; as well as
Formal/literary equivalent of だけでなく. Used to add another element, often with a following も or さえ.
See also: だけでなく
彼は日本語のみならず、英語も流暢に話す。
He speaks not only Japanese but also English fluently.
expression, conjunction
Used at the beginning of a sentence to add information, similar to さらに or そのうえ. Formal register.
この店は値段が高い。のみならず、サービスも悪い。
This shop is expensive. Moreover, the service is poor.