# hypotenuse

The hypotenuse is the longest side of a right triangle –
the one opposite the right angle. The word comes from the Greek roots *hypo* meaning "under" (which also appears, for example, in "hypodermic"
– "under the skin") and *tein* or *ten*, for stretch.
Thus hypotenuse is the line segment "stretched under" the right angle. See
also Pythagoras' theorem.