# triangle or triangular or triangularly

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##### Member
I want to describe a piece of cardboard that cut out like a triangle. How can I describe it using a compound adjective?

1) It's a triangle shaped piece of cardboard.
2) It's a triangular shaped piece of cardboard.
3) It's a triangularly shaped piece of cardboard.

Which one sounds best?
And my grammar checker says that I have to use a hyphen for 1 and 2. Is that correct?

• #### Uncle Jack

##### Senior Member
I would use (1) with a hyphen, or "triangular" without "shaped".

#### heypresto

##### Senior Member
Me too.

And definitely not 3), with or without a hyphen.

##### Member
Thanks,
What about other geometric shapes like circle, square and cube?
Do you say, circle-shaped, square-shaped and cube-shaped?
I feel that for cube maybe it's better to say cubically shaped. What do you guys think?

#### entangledbank

##### Senior Member
We'd naturally use the adjectives for a circular piece and a square piece, like a triangular piece. ('Square' is adjective as well as noun.) So also more mathematical terms like pentagonal. Probably for a cube we'd be more likely to use the noun 'cube': a wooden cube, a sugar cube, a cube of sugar.

#### heypresto

##### Senior Member
Probably for a cube we'd be more likely to use the noun 'cube'
Or 'cubic'.

I can't imagine saying 'cubically shaped'

#### Edinburgher

##### Senior Member
I would not use "shaped" at all. It's a triangular piece of cardboard or a triangle of cardboard or a cardboard triangle.

##### Member
We'd naturally use the adjectives for a circular piece and a square piece, like a triangular piece. ('Square' is adjective as well as noun.) So also more mathematical terms like pentagonal. Probably for a cube we'd be more likely to use the noun 'cube': a wooden cube, a sugar cube, a cube of sugar.
That is not the problem, I know how to use adjectives.
The thing is, there are many types of compound adjectives and 3 of those are: 1) Noun+past participle (i.e sun-dried), 2) Adjective+past participle (i.e short-lived) 3) Adverb+past participle (i.e well-paid)
I want to know that with the participle "shaped" which one I should use, an adjective, an adverb or a noun?
Circle-shaped, circular-shaped or circularly shaped? To me, circle-shaped sounds natural. same for triangle-shaped and square-shaped. I want to know whether this is like a grammar rule where we use geometric nouns with the participle ''shaped''.
Obviously this is a very specific example and I couldn't find any related topics, so I was hoping native speaker could maybe help shed some light on the matter.
I usually try to learn English through listening and reading and not grammar books. That's how natives of any language learn how to speak their language and I think that is the best approach, that's why I said all those examples I've highlighted sound natural to me. But sometimes the differences in English and my native language (Farsi) defy my logic and considering that I wanted to know whether I was right on point or totally off-target.

#### entangledbank

##### Senior Member
Noun-shaped is common, when there is no specific adjective for the shape: there are kidney-shaped swimming pools and heart-shaped birthmarks and lemon-shaped plastic containers of lemon juice. But it is rather odd to call something circle-shaped when there is a simpler way. Of the three possibilities, circle-shaped sounds most natural because it reminds us of heart-shaped; but it's not what we'd say.

#### Edinburgher

##### Senior Member
I want to know that with the participle "shaped" which one I should use, an adjective, an adverb or a noun?
I see. Only the noun, preferably with hyphen. An L-shaped room. Bear-shaped wine gums.
It's just that with basic geometric shapes, like circles, triangles, etc., we tend to prefer other ways of saying it, without "shaped".

Cross-posted and agreeing with EB.
I'm intrigued by "noun-shaped", though. I don't think I could describe the shape of a noun.