crust

Etymology

From Middle English cruste, from Anglo-Norman and Old French cruste, from Latin crusta (“hard outer covering”), from Proto-Indo-European *krustós (“hardened”), from *krews- (“to form a crust, begin to freeze”), related to Old Norse hroðr (“scurf”), Old English hruse (“earth”), Old High German hrosa (“crust, ice”), Latvian kruvesis (“frozen mud”), Ancient Greek κρύος (krúos, “frost, icy cold”), κρύσταλλος (krústallos, “crystal, ice”), Avestan 𐬑𐬭𐬎𐬰𐬛𐬭𐬀- (xruzdra-, “hard”), Sanskrit क्रूड् (krūḍ, “thicken, make hard”).

noun

1. A more solid, dense or hard layer on a surface or boundary.
2. The external, hardened layer of certain foodstuffs, including most types of bread, fried meat, etc.
3. An outer layer composed of pastry
4. The bread-like base of a pizza.
5. (Britain, Australia, New Zealand, Ireland, Canada) A slice of bread cut from the end of a loaf; the heel.
6. (geology) The outermost layer of the lithosphere of the Earth.
   The crust (a mere 1% of the Earth's volume) is made of lighter melt products from the mantle. 2012, Chinle Miller, In Mesozoic Lands: The Mesozoic Geology of Arches and Canyonlands National Parks, Kindle edition
7. (astronomy, by extension) The outermost layer of any terrestrial planet.
8. The shell of crabs, lobsters, etc.
9. (Britain, Australia, informal) A living.
   to earn one's crust
   Like most of us, I am frequently asked by friends and people I meet in business situations or round the dinner table what I do to earn my crust. 1999, Norman Longworth, Making Lifelong Learning Work: Learning Cities for a Learning Century, Psychology Press, page 1
10. (uncountable, informal) Nerve, gall.
    You've got a lot of crust standing there saying that.
11. (UK, Australia, slang, dated) The head.
    “Well, all I can say is that if yer don't take yer dial outer the road I'll bloomin' well take an' bounce a gibber off yer crust.” 1918, Norman Lindsay, The Magic Pudding, page 90
12. (music) Ellipsis of crust punk (a subgenre of punk music)

verb

1. (transitive) To cover with a crust.
   The whole body is crusted over with ice. 1662, Robert Boyle, An Account of Freezing
   Their minds are crusted over, like diamonds in the rock. 1711, Henry Felton, Dissertation on Reading the Classics
2. (intransitive) To form a crust.