温める, 暖める, あたためる, あっためる
Conjugated: 暖めた
Ichidan verb, Transitive
1. to warm (up), to heat (up)
Only 温める
2. to sit on (an idea, plan, etc.), to keep to oneself, to nurse, to mull over
See 旧交を温める
3. to renew (an old friendship)
4. to take for oneself
ミルクを温めてくれませんか。