hot or warm thing

(waterleft) + (sun, day) + (plate)
★★★★☆
12 strokes
DUPE

Onyomi

ON

Mnemonic

The sun shining ON the plate full of water, made the water warm.

Kunyomi

あたた*かい also abbreviated to あったかい: warm thing (puppy, or puddle under your bed )
★★★★☆
( ) あたた*める I warm up (the muffins)
★★★☆☆
( ) あたた*まる something gets warmed up
★★★☆☆

Jukugo

温度(おんど)

temperature ★★★☆☆
(hot or warm thing) + (times) = 温度 (temperature)

温泉(おんせん)

hot spring bath ★★★☆☆
(hot or warm thing) + (spring) = 温泉 (hot spring bath)

hot spring baths (although most onsen use artificially heated water from regular wells these days)

Synonyms

warm
暖かい    温かい