previous existence; previous life
Refers to a life before the current one, often in a Buddhist or reincarnation context. Can also be used more loosely for a past era or former state of being.
He says he has memories of his previous life.
In a previous existence, I might have been a different person.
Compound of 前 (まえ, 'before') + の (possessive particle) + 世 (よ, 'world, age, life'). The reading よ for 世 is an older native Japanese reading.