Definition of arch
(Entry 1 of 9)
1 : a typically curved structural member spanning an opening and serving as a support (as for the wall or other weight above the opening)
2a : 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
arch
verbarched; arching; arches
Definition of arch (Entry 2 of 9)
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.
arch
adjectiveDefinition of arch (Entry 3 of 9)
2a : 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
arch
abbreviation (1)Definition of arch (Entry 4 of 9)
Arch
abbreviation (2)Definition of Arch (Entry 5 of 9)
arch-
prefix (1)Definition of arch- (Entry 6 of 9)
1 : chief : principal
archfiend
2 : extreme : most fully embodying the qualities of the kind
archconservative
arch-
prefix (2)Definition of arch- (Entry 7 of 9)
— see archi-
-arch
noun combining formDefinition of -arch (Entry 8 of 9)
: ruler : leader
matriarch
-arch
adjective combining formDefinition of -arch (Entry 9 of 9)
: having (such) a point or (so many) points of origin
endarch
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Test Your Vocabulary
Slippery Words Quiz—Changing with the Times
- What is an earlier meaning of nice?

Test your knowledge - and maybe learn something along the way.
TAKE THE QUIZ
A daily challenge for crossword fanatics.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridgedWords at Play
Ask the Editors
Word Games
Slippery Words Quiz—Changing with the Times
Do you know these earlier meanings of words?
Take the quizWords of Snow and Ice Quiz
A selection of words from the chillier parts of t...
Take the quizTrue or False?
Test your knowledge - and maybe learn something a...
Take the quizWord Winder's CrossWinder Play the game
Share arch
Time Traveler for arch
The first known use of arch was in the 13th century
See more words from the same century