In the manner or style of a curmudgeon; characterized by grumpiness, ill temper, and complaints.
From 'curmudgeon' (noun) plus '-ly' (adverb/adjective-forming suffix), creating an adjective or adverb that describes curmudgeon-like behavior.
Interestingly, 'curmudgeonly' as an adjective is often more intensely grumpy than 'curmudgeonish'—the '-ly' ending tends to make it sound more committed to the crankiness, while '-ish' feels more casual.
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