Illustration of arch
- 1 round
- imp impost
- sp springer
- v voussoir
- k keystone
- ext extrados
- int intrados
- 2 horseshoe
- 3 lancet
- 4 ogee
- 5 trefoil
- 6 basket-handle
- 7 Tudor
1
: a typically curved structural member spanning an opening and serving as a support (as for the wall or other weight above the opening)
2
a
: something resembling an arch in form or function
especially
: either of two vaulted portions of the bony structure of the foot that impart elasticity to it
b
: something that has a curved shape like an arch
There was a slight arch in her eyebrows.
an arch in the cat's back
3
: archway
arched; arching; arches
1
: to cover or provide with an arch
A bridge arches the stream.
2
: to form into an arch
She arched her eyebrows.
1
: to form an arch
Trees arch above the promenade.
2
: to take an arch-shaped course
The ball arched toward the basket.
2
a
: mischievous, saucy
b
: marked by a deliberate and often forced playfulness, irony, or impudence
known for her arch comments
… decided to answer them by being teacherly in a sort of arch, Olympian way.—
Gerald Early
Gerald Early
archness
noun
1
: chief : principal
archfiend
2
: extreme : most fully embodying the qualities of the kind
archconservative
see archi-
: ruler : leader
matriarch
: having (such) a point or (so many) points of origin
endarch
Did you know?
As a prefix, arch- appears in a number of titles referring to positions of superiority, such as archduke and archbishop; it can also mean "chief" (as in archnemesis) or "extreme" (archconservative). It comes from the Greek verb archein, meaning "to begin or to rule."
Examples of arch in a Sentence
Noun
There was a slight arch to her eyebrows.
an arch in the cat's back
Verb
The cat arched its back.
She arched her eyebrows in surprise.
A tree arches over the road.
She arched backward to begin the exercise.
Adjective
a politician known for his arch humor
The novel is never mocking or arch in its tone.
Recent Examples on the Web
Rebecca Mead, New Yorker, 9 Feb. 2026
The flat brow, or straight brow, is shaped in a straight line rather than the traditional arch.
—Audrey Noble, Vogue, 9 Feb. 2026
Paul Cappiello, Louisville Courier Journal, 13 Feb. 2026
Back on the highway, the rearview mirror showed the clouds had lifted, the waters were still, and a rainbow had arched across the sky.
—Marlise Kast-Myers, San Diego Union-Tribune, 8 Feb. 2026
Sean Nevin, NBC news, 14 Feb. 2026
And Ed went to our arch-rival, Mississippi State, and was a superstar there (2005-07).
—Mitch Light, New York Times, 11 Feb. 2026
See All Example Sentences for arch
Examples are automatically compiled from online sources to
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Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
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Noun
The work is a stone arch that, rather than traversing a stream from one bank to another, stands in the water lengthwise, aligned with the rushing current, evoking a leaping salmon.
—Rebecca Mead, New Yorker, 9 Feb. 2026
The flat brow, or straight brow, is shaped in a straight line rather than the traditional arch.
—Audrey Noble, Vogue, 9 Feb. 2026
Verb
Growing about two feet tall and three feet wide, its delicate blades arch and flutter in the breeze to great effect.
—Paul Cappiello, Louisville Courier Journal, 13 Feb. 2026
Back on the highway, the rearview mirror showed the clouds had lifted, the waters were still, and a rainbow had arched across the sky.
—Marlise Kast-Myers, San Diego Union-Tribune, 8 Feb. 2026
Adjective
Having had a seven-second lead in the race after the first leg, Andersson slips out on a turn, allowing arch-rivals Norway through.
—Sean Nevin, NBC news, 14 Feb. 2026
And Ed went to our arch-rival, Mississippi State, and was a superstar there (2005-07).
—Mitch Light, New York Times, 11 Feb. 2026
See All Example Sentences for arch
Cite this Entry
“Arch.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/arch. Accessed 16 Feb. 2026.
Copy CitationKids Definition
arch
2 of 4 verb1
: to cover or provide with an arch
2
: to form into an arch
3
: to take an arch-shaped path
arch-
4 of 4 prefix
: chief : principal
archenemy
Etymology
Noun
Middle English arche "arch," from early French arche (same meaning), derived from Latin arcus "bow (weapon)"
Adjective
from arch- (prefix)
Prefix
derived from Greek archein "to begin, rule"
Medical Definition
arch
noun1
: an anatomical structure that resembles an arch in form or function: as
a
: either of two vaulted portions of the bony structure of the foot that impart elasticity to it:
(1)
: a longitudinal arch supported posteriorly by the basal tuberosity of the calcaneus and anteriorly by the heads of the metatarsal bones
(2)
: a transverse arch consisting of the metatarsals and first row of tarsals and resulting from elevation of the central anterior portion of the median longitudinal arch
2
: a fingerprint in which all the ridges run from side to side and make no backward turn
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