Having a hard, crisp outer layer, like bread; or in bad mood, grumpy, or ill-tempered.
From Old French 'crouste,' derived from Latin 'crusta' (hard shell or rind). Used literally for bread, figuratively for personality since the 16th century.
The term 'crusty old sailor' or 'crusty character' might come from the idea that people harden on the outside with age and experience—but interestingly, crusty bread actually gets better with time and develops deeper flavor!
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