equilateral
LowTechnical / Mathematical / Formal
Definition
Meaning
A plane figure (especially a triangle) having all sides equal in length.
Used more broadly to describe any object or shape where all sides or facets are equal. In a figurative sense, it can describe a situation or relationship where all parties or elements are equal.
Linguistics
Semantic Notes
Primarily a mathematical term; outside of mathematics, its use is metaphorical and rare. Its core meaning is unambiguously geometric.
Dialectal Variation
British vs American Usage
Differences
No significant differences in meaning or usage. Spelling conventions (e.g., '-ise' vs '-ize' for related words like 'equalise/equalize') do not apply to this specific word.
Connotations
Identical technical connotations. In everyday figurative use, equally rare in both varieties.
Frequency
Equally low frequency in both dialects, confined primarily to technical contexts.
Vocabulary
Collocations
Grammar
Valency Patterns
[be] equilateralan equilateral [noun]Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “None in common usage. Figurative: 'an equilateral relationship' (implying equal power/status).”
Usage
Context Usage
Business
Rare. Possible in metaphors: 'The three partners formed an equilateral alliance.'
Academic
Common in geometry, trigonometry, engineering, and design contexts.
Everyday
Rare, except when recalling school geometry.
Technical
Standard term in mathematics, architecture, crystallography, and technical drawing.
Examples
By Part of Speech
adjective
British English
- The courtyard was paved with equilateral triangles of slate.
- She drew a perfectly equilateral hexagon, which is impossible.
American English
- An equilateral triangle is a special case of an isosceles triangle.
- The logo featured an abstract, equilateral shape.
Examples
By CEFR Level
- A triangle with three equal sides is called equilateral.
- In the test, we had to calculate the area of an equilateral triangle.
- The crystal structure was analysed and found to form equilateral prisms.
- Their agreement was intended to be equilateral, with no single party holding more influence.
- The architect's design utilised a series of nested equilateral polygons to create an illusion of infinite regress.
- The treaty aimed for an equilateral balance of power among the three signatory nations.
Learning
Memory Aids
Mnemonic
EQUI-LATERAL: EQUI (equal) + LATERAL (side). 'Equal-sided'.
Conceptual Metaphor
EQUALITY IS GEOMETRICAL BALANCE (e.g., 'an equilateral partnership').
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- The Russian term 'равносторонний' (ravnostoronniy) maps directly and accurately. No major trap. Be aware of stress: равносторОнний.
Common Mistakes
- Confusing 'equilateral' (all sides equal) with 'isosceles' (two sides equal).
- Using 'equiangular' interchangeably (true only for equilateral triangles).
- Mispronunciation: /ɛkwɪˈlætərəl/ instead of /ˌiːkwɪˈlætərəl/.
Practice
Quiz
In which field is the word 'equilateral' most frequently and precisely used?
FAQ
Frequently Asked Questions
No. While 'equilateral triangle' is the most common use, any polygon with all sides of equal length can be described as equilateral (e.g., an equilateral pentagon).
For triangles, they coincide: an equilateral triangle is always equiangular. For other polygons, this is not necessarily true. A rhombus can be equilateral (all sides equal) but not equiangular, while a rectangle is equiangular but not equilateral.
Yes, though less common. It can function as a noun meaning 'a side that is equal to others' or, more often, short for 'equilateral triangle' (e.g., 'Construct an equilateral on this base line').
In technical drawings and mathematics, it is often abbreviated as 'eq.' or noted with the symbol for congruence on the sides of a triangle.