Word Confusion: Arc versus Arch

Plural for the noun: arcs
Gerund: arcing, arcking

Third person present verb: arcs
Past tense or past participle: arced, arcked
Present participle: arcing, arcking

Plural for the noun: arches
Gerund: arching

Third person present verb: arches
Past tense or past participle: arched
Present participle: arching

American Red Cross

[Medical] AIDS-related complex

Adjective:
Arc or angle (corresponding to the) sine (of so many degrees) ¹

Noun:
Part of the circumference of a circle or other curve ²

Luminous electrical discharge between two electrodes or other points

[In a novel, play, or movie] The development or resolution of the narrative or principal theme

Verb, intransitive:
Move with a curving trajectory ²

Form an electric arc [the noun]

Noun:
Curved symmetrical structure spanning an opening and typically supporting the weight of a bridge, roof, or wall above it ²

• Archway

A shape resembling such a structure

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

Prefix:
A combination form: arch- ³

Chief

Principal

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

Suffix:
A combination form to form nouns: -arch ⁴

Denoting a ruler or leader

Verb, intransitive:
Have the curved shape of an arch ³

Form an arch

Take an arch-shaped course

Verb, transitive:
Provide a bridge, building, or part of a building with an arch ³

Cover or provide with an arch

Form into an arch

“A rarely used term today, ARC described people with HIV infection who had only mild symptoms of illness, such as swollen lymph glands” (Stöppler).

Publishers provide ARCs to reviewers for advanced publicity.

Adjective:
The arc whose cosine is χ is the same as the angle whose cosine is χ (Inverse).

We’ll need an arc lamp for this project.

Noun:
He swung his flashlight in a wide arc.

There’s a built-in arc to the story.

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.

I have no idea whether they touched the power lines or arced.

It has such lovely high arched windows.

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

The delicate arch of her eyebrows was carefully plucked.

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

He is the archbishop.

He is an arch-scoundrel.

Suffix:
He is the monarch of the seas.

She was the matriarch of the clan.

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.

1. Circa 1949.
2. Late Middle English (denoting the path of a celestial object, especially the sun, from horizon to horizon) via the Old French from the Latin arcus meaning bow, curve.

1. Mid-sixteenth century from arch- because of its association with words such as rogue.
2. Middle English with its first known use in the 14th century.
3. From the Latin via Greek, arkhi- from arkhos meaning chief.
4. From the Greek arkhos meaning ruling and from arkhein meaning to rule.