arc, ark

Arc or arc means a curve or a section of a circle--
An arc is usually measured in degrees, like a circle.
90° ( ninety degrees ) of  arc means 1/4 ( one quarter ) of a circle, also called a quadrant.
Arc also means to move in a curve--
He nearly fell over backwards while trying to watch the arc of the ball.
Arc may mean a curved path--
They are trying to plot the arc of the sun, using an old telescope and a camera.

Ark or ark ( rhymes with arc ) means a ship, as in the story of Noah and the ark, or, in the more recent past, a flat-bottomed river boat--
The children never tire of the story of Noah and the ark.
In the nineteenth century, they piloted an ark up and down the Mississippi.

Ark or ark also means a chest or box, most commonly one used to hold a sacred or religious object--
Some people believe that they may find the original Ark of the Covenant some day.
He's reading one of those adventure stories about an ancient ark and the people who find it.

Now that you know that, you can say--
"When Noah saw the arc of the rainbow, he knew that his ark and its passengers would be safe."

Note--"Ark." is an old-fashioned abbreviation for "Arkansas"--
This old envelope is addressed to someone in Little Rock, Ark.

Note # 2--"--arch" ( rhymes with arc when used as a suffix, at the end of a word ) means ruler or important person--
Herod was the tetrarch of Galilee during the reign of Tiberius Caesar.

Note #3--"archeo--"  is a prefix ( forms the beginning of a word ) meaning primitive--
He wants to study archaeology, and dig up old ruins.

Note # 4--Not to be confused with "arch", meaning a curved building unit used to span a door or window--
Notice how the stones that form the arch fit together perfectly.

Arch also means chief or most important--
Moriarty was Sherlock Holmes' archenemy.

Arch may mean sly or devious--
He tried to look serious, but she noticed his arch smile.

Note # 5--"Arch." or "arch." may be an abbreviation of several different words--archaeology, archipelago, archaic, architect, archive, and others. You will need to read the context of the abbreviation to find out what it stands for.

Note # 6--Arch ( a proper noun, always capitalized ) may also be a nickname for "Archibald"--
Ask Arch if he's free for lunch.

Note # 7--"ARC" stands for the American Red Cross, or it may be an abbreviation or acronym for other organizations.