Word Confusion: Arc versus Arch

Posted February 6, 2013 by Kathy Davie in Author Resources, Editing, Self-Editing, Word Confusions, Writing

This confusion has cropped up a few times in the past couple of months and has bothered me enough to explore the differences. Part of the problem is that both words are based on the same root word, arcus, from the Latin.

Arc evolved into a term referring to a path while arch came to refer to shapes as in the arch of a foot, an eyebrow, or a part of a building. One trick I’ve found useful when trying to differentiate between them is to keep in mind that an arc (when not playing adjective or noun!) moves while an arch is not about movement.

Word Confusions…

…started as my way of dealing with a professional frustration with properly spelled words that were out of context in manuscripts I was editing as well as books I was reviewing. It evolved into a sharing of information with y’all. I’m hoping you’ll share with us words that have been a bête noir for you from either end.

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Arc Arch
Credit to: Apple Dictionary.com; Merriam-Webster

Image courtesy of Wikimedia Commons

I think the photographer is Gary Dee

Image courtesy of
Yvette Cendes

Delicate Arch at Arches National Park

Part of Grammar:
Adjective 1; Noun 2;
Verb, intransitive 2

Plural for the noun and third person present verb: arcs
Past tense or past participle: arced
Gerund or Present participle: arcing

Adjective 3; Noun 4; Prefix 5; Suffix 6;
Verb, intransitive & transitive (usually used as an adjective) 4

Plural for the noun and third person present verb: arches
Past tense or past participle: arched
Gerund or Present participle: arching


Arc or angle (corresponding to the) sine (of so many degrees) (Merriam-Webster)

Part of the circumference of a circle or other curve

Luminous electrical discharge between two electrodes or other points

[Acronym] Advanced Reading Copy

[Acronym] American Red Cross

[Medical acronym] AIDS-related complex

Verb, intransitive:
Move with a curving trajectory

Form an electric arc [the noun]


Deliberately or affectedly playful and teasing

Curved symmetrical structure spanning an opening and typically supporting the weight of a bridge, roof, or wall above it

  • Archway

A shape resembling such a structure

Raised area on the bottom of the foot that is formed by a curved section of bones

A combination form: arch-


  • Preeminent of its kind
  • [In unfavorable senses] Out-and-out

A combination form to form nouns: -arch

Denoting a ruler or leader

Verb, intransitive:
Have the curved shape of an arch

Form an arch

Take an arch-shaped course

Verb, transitive:
Provide a bridge, building, or part of a building with an arch

Cover or provide with an arch

Form into an arch

The arc whose cosine is χ is the same as the angle whose cosine is χ (Wikipedia).

We’ll need an arc lamp for this project.

He swung his flashlight in a wide arc.

Publishers provide ARCs to reviewers for advanced publicity.

The electric arc shone too bright at that moment.

Verb, intransitive:
The ball arced across the room.

Check that switches operate properly with no sign of arcing.

She made arch observations about the most mundane matters.

It has such lovely high arched windows.

Napoleon constructed a monumental arch, L’Arc de Triomphe to celebrate his gains.

The delicate arch of her eyebrows was carefully plucked.

He is my archenemy, and I will take him down.

He is the archbishop.

He is an arch-scoundrel.

He is the monarch of the seas.

Verb, intransitive:
A beautiful bridge that arched over a canal.

The vine arched over his evening seat.

Verb, transitive:
Some yoga positions require that you arch your back.

Something scared my cat, for she’s arching her back.

Abbreviation: archaic, archaism, archery
Adverb: archly
Noun: archness
History of the Word:
1 circa 1949

2 Late Middle English

3 Mid-sixteenth century from arch- because of its association with words such as rogue

4 Middle English

First known use: 14th century

5 From Latin via Greek, arkhi- from arkhos meaning chief.

6 From the Greek arkhos meaning ruling and from arkhein meaning to rule

C’mon, get it out of your system, bitch, whine, moan…which words are your pet peeves?

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Pinterest Photo Credits:

The “St. Louis Gateway Arch” is Dirk Beyer’s own work [GFDL, CC-BY-SA-3.0 or CC BY-SA 2.5], via Wikimedia Commons. Beyer notes that he brightened the original.

This U.S. Navy photo was taken by Mass Communication Specialist 3rd Class Adam K. Thomas of US Navy 100806-N-6720T-005 Hull Maintenance Technician Fireman Zac Vess uses an arc welder to reattach an electrical outlet mounting post to the hull of USS George Washington (CVN 73) and is in the public domain, via Wikimedia Commons.