A person or thing that equalizes sides or makes something equal-sided; a geometric figure with equal sides.
From Latin 'aequi-' (equal) and 'latus' (side). The term was used both as an agent noun (one who equalizes) and to describe symmetric shapes.
You'll almost never hear this word, but mathematicians will instantly understand it means something with equal sides—it's been completely replaced by 'equilateral' which became the standard form.
Complete word intelligence in one call. Free tier — 50 lookups/day.