A temporary loss of consciousness (fainting, syncope); a state in which someone may pass out or become unresponsive, often used in medical contexts.
暑さで失神したらすぐに涼しい場所で休ませて水分を補給する。
If someone faints from the heat, have them rest in a cool place immediately and give them fluids.
彼は貧血で失神して病院に運ばれた。
He fainted due to anemia and was taken to the hospital.
運転中に失神すると非常に危険なので、持病がある場合は医師と相談するべきだ。
Fainting while driving is very dangerous, so if you have a condition you should consult a doctor.