温まる
あたたまる · atatamaru · JLPT N3 · verb-godan
to warm oneself
♨️ 温 = warm + -まる ending: you get warm yourself, like あたたかい (warm)
Shares its root with あたたかい (warm). The -まる ending marks something that happens on its own: 温まる means to get warm. Its pair 温める (atatameru) means to warm something else up, like heating up soup.