# equilateral and equalateral

**URL:** <https://boards.straightdope.com/t/equilateral-and-equalateral/339440>\
**Category:** Factual Questions\
**Created:** [January 11, 2006, 4:21am UTC](https://boards.straightdope.com/t/equilateral-and-equalateral/339440 "2006-01-11T04:21:08Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![sharkattack](https://avatars.discourse-cdn.com/v4/letter/s/76d3ee/32.png) [@sharkattack](https://boards.straightdope.com/u/sharkattack)\
**Post date:** [January 11, 2006, 4:21am UTC](https://boards.straightdope.com/t/equilateral-and-equalateral/339440/1 "2006-01-11T04:21:08Z")

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why were equilateral triangles spelled this way, or should it be 1+5 equils 6?

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**Author:** ![groman](https://avatars.discourse-cdn.com/v4/letter/g/73ab20/32.png) [@groman](https://boards.straightdope.com/u/groman)\
**Post date:** [January 11, 2006, 4:27am UTC](https://boards.straightdope.com/t/equilateral-and-equalateral/339440/2 "2006-01-11T04:27:54Z")

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Probably because the english prefix “equi-” means equal, I’m guessing from the latin prefix aequi-.

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**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\
**Post date:** [January 11, 2006, 4:38am UTC](https://boards.straightdope.com/t/equilateral-and-equalateral/339440/3 "2006-01-11T04:38:28Z")

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> [@groman](#):
>
> Probably because the english prefix “equi-” means equal, I’m guessing from the latin prefix aequi-.

Precisely. _aequalis_ was one of several words derived from “aequi-”, and it’s the origin for “equal.”

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**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\
**Post date:** [January 11, 2006, 4:44am UTC](https://boards.straightdope.com/t/equilateral-and-equalateral/339440/4 "2006-01-11T04:44:27Z")

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It’s important for the OP to realize that the word _equilateral_ breaks down to _equi-_ (equal) and _-lateral_ (side), not _equil-ateral_. That may be some of the source of the confusion.

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**Author:** ![Giles](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/giles/32/60_2.png) [@Giles](https://boards.straightdope.com/u/Giles)\
**Post date:** [January 11, 2006, 11:42am UTC](https://boards.straightdope.com/t/equilateral-and-equalateral/339440/5 "2006-01-11T11:42:22Z")

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And the word “lateral” means to do with sides. So “equilateral” means, literally, equal-sided.

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**Author:** ![sharkattack](https://avatars.discourse-cdn.com/v4/letter/s/76d3ee/32.png) [@sharkattack](https://boards.straightdope.com/u/sharkattack)\
**Post date:** [January 11, 2006, 12:28pm UTC](https://boards.straightdope.com/t/equilateral-and-equalateral/339440/6 "2006-01-11T12:28:01Z")

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> [@Polycarp](#):
>
> Precisely. _aequalis_ was one of several words derived from “aequi-”, and it’s the origin for “equal.”

Thanks…