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to warm (up); to heat (up)
to sit on (an idea, plan, etc.); to keep to oneself; to nurse; to mull over
to renew (an old friendship)
to take for oneself
冷めてしまったコーヒーをレンジで温めた。
I warmed up the cold coffee.
何年もアイデアを温めてきた。
I have been nursing the idea for years.
温泉のお風呂のお湯を温めた。
I warmed the bath water.