眠る, 睡る, ねむる, ねぶる
Conjugated: 眠れなかった
Godan verb, Intransitive, See 寝る・3
1. to sleep
2. to die, to rest (in peace), to lie (buried), to sleep (in the grave)
Only ねむる
3. to lie idle (e.g. of resources), to lie unused, to lie untapped, to lie untouched
Archaism
4. to close one's eyes
彼は今地下に眠っている。