somewhat or characteristically gruff; having a tendency to be rough or unfriendly in manner.
From 'gruff' plus the adjective-forming suffix -y, similar to 'gruffish' but using a different morphological path.
Words ending in -y that mean 'having the quality of' (like 'gruffy,' 'rainy,' 'friendly') come from an ancient English pattern, and the -y suffix started as a completely different part of speech before becoming this productive qualifier.
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