also: あっためる
ichidan verb, transitive verb
warm up; heat up
General physical warming: food, drinks, rooms, body parts. Both 温める and 暖める are used, with 暖める more common for ambient warmth.
スープを温めてから食べましょう。
Let's warm up the soup before eating.
寒いのでストーブで部屋を暖めた。
It was cold, so I warmed the room with the heater.
ichidan verb, transitive verb
keep to oneself; sit on; nurse; mull over
Only when written 温める
Figurative use with 温める: to hold onto an idea, plan, or feeling without revealing it, often with the nuance of developing it privately.
彼は新しい事業のアイデアを長い間温めていた。
He had been nursing the idea for a new business for a long time.
その計画はまだ誰にも話さずに温めておこう。
Let's keep that plan to ourselves for now without telling anyone.
ichidan verb, transitive verb
Only when written 温める
Used almost exclusively in the set phrase 旧交を温める (to renew an old friendship). Rare outside this collocation.
See also: 旧交を温める
同窓会で旧交を温めることができて嬉しかった。
I was happy to be able to renew old friendships at the class reunion.
ichidan verb, transitive verb
take for oneself
Only when written 温める
Rare, possibly obsolete usage meaning to appropriate or pocket something. Modern Japanese would typically use 自分のものにする or similar.
古い文献では、利益を温めるという表現が見られることがある。
In old documents, one can sometimes see the expression 利益を温める, meaning to take the profit for oneself.