expression
no matter (what, who, etc.); even if
Follows a noun or a question word (e.g., 何, 誰, どこ) to mean 'no matter what/who/where' or 'even if'. Often used in formal or written contexts.
理由が何であれ、遅刻は遅刻だ。
No matter what the reason is, being late is being late.
誰であれ、この部屋には入れない。
No matter who it is, they cannot enter this room.
expression
Used in the pattern ...であれ...であれ to list alternatives, meaning 'whether ... or ...'. Formal and often written.
雨であれ雪であれ、試合は予定通り行われる。
Whether it rains or snows, the game will be held as scheduled.
expression
Imperative form of である, meaning 'be'. Rare and literary; not used in modern conversational Japanese.
See also: である
「強くであれ」と彼は言った。
"Be strong," he said.