# It's <triangle-shaped> <triangle>.

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#### Kenny Chang

##### Senior Member
Hello, everyone. If there's a question "What is the shape of this stone", will the answer be like "It's triangle-shaped" or "It's triangle"?
"It's square-shaped" or "It's square"
"It's rectangle-shaped" or "It's rectangle"
Can shapes like triangle, square, rectangle themselves be used as adjectives? Thank you.

• #### much_rice

##### Senior Member
Can shapes like triangle, square, rectangle themselves be used as adjectives?
No, but you can still use them as nouns:
—"What shape are these three rocks?"
—"This one's a triangle, this one's a square, and this one's a rectangle."

The shapes also have their adjective forms (for square it's the same!):
—"What shape are these three rocks?"
—"This one's triangular, this one's square, and this one's rectangular."

As a last resort, you can use "-shaped":
—"What shape are these three rocks?"
—"This one's triangle-shaped, this one's square-shaped, and this one's rectangle-shaped."

But these last examples with "-shaped" are not as commonly used, and they sound clumsy. I would only use them if there's a really bizarre shape to the rock: "This rock is eagle-shaped, this one's skull-shaped, and this one's shaped like a B-52 jet."

Edit: spelling & punctuation

#### Myridon

##### Senior Member
For the nouns square, rectangle, and triangle, the adjectives are square, rectangular, and triangular.

#### dojibear

##### Senior Member

You can use a noun to say "it's triangle-shaped", "it's a triangle", "it's a rectangle", "it's rectangle-shaped".

You can use adjectives to say "it's triangular", "it's rectangular", "it is square", "it is round".

"Square" is both an adjective and a noun. But the other shapes are not.

#### RM1(SS)

##### Senior Member
"Square" is both an adjective and a noun.
As is "oval". Can't think of any others, though.

#### Kenny Chang

##### Senior Member
Thank you everyone for your detailed explanation!

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