What it means
もしも means “if,” “in case,” or “supposing.” It adds emphasis to a hypothetical condition and often introduces a possibility that the speaker wants to consider. It commonly appears before a clause ending in a conditional form such as たら, なら, ば, or と. It is generally stronger or more emphatic than もし, but the basic conditional meaning comes from the conditional form that follows.
Usage note
もしも is an adverb, so it does not mark the condition by itself. A conditional ending such as たら, なら, ば, or と normally follows the clause introduced by もしも.
How to use it
もしも雨が降ったら、試合は中止になります。
If it rains, the match will be canceled.
もしも雨が降ったら、試合は中止になる。
If it rains, the match will be canceled.
Example sentences
もしも電車が遅れたら、駅の案内所で遅延証明書をもらってください。
If the train is delayed, please get a delay certificate at the station information desk.
もしも明日雪が降ったら、学校は休みになります。
If it snows tomorrow, school will be closed.
もしも大切な書類をなくしたなら、すぐに会社へ連絡してください。
If you lose an important document, please contact the company immediately.