1
a
: the hardened exterior or surface part of bread
b
: a piece of this or of bread grown dry or hard
2
a
: the pastry shell of a pie : piecrust
b
: the bready layer that forms the foundation of a pizza
3
: a hard or brittle external coat or covering: such as
a
: a hard surface layer (as of soil or snow)
b
: the outer part of a planet, moon, or asteroid composed essentially of crystalline rocks
c
: a deposit built up on the interior surface of a wine bottle during long aging
d
: an encrusting deposit (as of the eye) of dried secretions or exudate
also : scab
4
: gall, nerve
crust verb
crustal adjective
crustless adjective

Examples of crust in a Sentence

Her children prefer to eat their sandwiches with the crust cut off. a pie with flaky crust He likes pizza with thin crust.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
All metals in this group are rare, with platinum, the most common among them, being only about one millionth of 1% of the Earth’s crust. Victor Rosario, Sacramento Bee, 26 Feb. 2025 Why Are Rare Earth Minerals So Important? Rare earth minerals, a blanket term for 17 metallic elements found in the earth's crust, possess unique properties such as magnetic capabilities, electrical conductivity and resistance to corrosion. Matt Robison, Newsweek, 25 Feb. 2025 The Earth's crust varies in thickness from about 5 to 75 km (3 to 47 miles), with the thinnest parts tending to be way out in the deep ocean. New Atlas, 23 Feb. 2025 However, the compass may still act erratically if Venus has localized regions of magnetized crust, though evidence of this is still lacking. Jake Parks, Discover Magazine, 21 Feb. 2025 See All Example Sentences for crust

Word History

Etymology

Middle English crouste, cruste, borrowed from Anglo-French & Latin; Anglo-French cruste, crouste, going back to Latin crusta "hard coating or surface layer, shell of an arthropod or crustacean, mineral flake, stone slab used in paneling," perhaps, if going back to *krus-to- "something crushed or pounded into a hard layer," from a zero-grade nominal derivative of Indo-European *kreu̯s- "beat, crush, pound," whence also Old English hruse "earth, ground," Old High German roso, rosa "crust, layer of ice" (going back to Germanic *hrusōn-) — more at anacrusis

Note: The hypothetical base *krus-to- is suggested by Michiel de Vaan, Etymological Dictionary of Latin and the Other Italic Languages (Leiden: Brill, 2008), p. 147, though the older handbooks (Walde-Hoffman, Ernout-Meillet) tend to support a connection with Greek krýos "icy cold, frost" and other derivatives, going back to a presumed homonymous *krus- (see cryo-). As de Vaan points out, however, Latin crusta does not mean "ice." The original sense of the Germanic noun *hrusōn- is not certain. Greek krýstallos "ice, rock crystal" is almost certainly unrelated (see crystal entry 1).

First Known Use

14th century, in the meaning defined at sense 1a

Time Traveler
The first known use of crust was in the 14th century

Browse Nearby Entries

Cite this Entry

“Crust.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/crust. Accessed 3 Mar. 2025.

Kids Definition

crust

noun
1
a
: the hardened outside surface of bread
b
: a piece of dry hard bread
2
: the pastry cover of a pie
3
a
: a hard surface layer
a crust of snow
b
: the outer part of the earth
crustal adjective

Medical Definition

crust

noun
1
2
: an encrusting deposit of serum, cellular debris, and bacteria present over or about lesions in some skin diseases (as impetigo or eczema)
crust verb

More from Merriam-Webster on crust

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!