What is the meaning of Equilateral?

Having all the sides equal.

Having all the faces equal.

Having the two sides equal, as a surface divisible by a longitudinal median line into two halves of the same form.

Having all the convolutions of the shell in one plane, chiefly of foraminifers.

A side exactly corresponding, or equal, to others.

A figure having all its sides equal.

Source: wiktionary.org