also: かねつむら
noun
uneven heating (of food)
Refers to hot and cold spots when heating food, especially in a microwave oven. Often used in cooking instructions and troubleshooting.
See also: 斑 (むら)
電子レンジで温めるとき、加熱ムラを防ぐために途中でかき混ぜてください。
When heating in a microwave, stir halfway to prevent uneven heating.
この冷凍食品は加熱ムラが起きやすいので、表示時間より長めに温めたほうがいい。
This frozen food tends to heat unevenly, so it's better to heat it a little longer than the indicated time.
むら by itself means unevenness, blotchiness, or inconsistency in general. 加熱ムラ specifically refers to unevenness in heating, especially in cooking.
Compound of 加熱 (かねつ, 'heating') and ムラ (むら, 'unevenness'). The katakana spelling ムラ is common in technical or culinary contexts.