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unevenness (of colour, paint, etc.); irregularity; nonuniformity; blotchiness
unevenness (of quality, results, behaviour, etc.); inconsistency; instability
fickleness; capriciousness; fitfulness
「斑」 has other readings with different meanings.
この壁の塗装には斑があって不均一です。
There is unevenness in this wall's painting.
彼の仕事ぶりには斑があって安定しません。
His work performance is inconsistent.
日焼けに斑ができてしまって困っています。
I got uneven tan marks.