The quality or state of being crusty, either having a hard outer layer or being irritable and grumpy.
From 'crusty' plus the suffix '-ness' (state or quality). 'Crusty' comes from Latin 'crusta' (hard outer layer). The figurative meaning developed from comparing a gruff person to the hardness of a crust.
One word captures two totally different ideas—the flaky-golden crust on bread AND a grumpy person's bad attitude—and linguists think the grumpiness developed because old, hardened things become brittle and irritable-seeming!
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