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if; in case; supposing
「若し」 has another reading with different meanings.
like; as if; the same as
もし明日あす雨あめだったら行きいきません。
If it rains, I won't go.
もし暇ひまなら来きてください。
If you're free, please come.
もしよければ手伝ってつだった方ほうがいい。
If you don't mind, please help.