Linguistically derived from “at-tawasut” (to stand in the middle/take a middle course) & “wasat” with the vowel movement is that which is between the two ends of something, like the centre of a circle; with a sukoon, an ambiguous name like the area inside a circle, for example.

From the original meaning, the Wasat of something is its straightest part. The Wasat of something is that which is between its two sides.