Sinus and Watershed

Sinus noun - An abnormal passage leading from a suppurating cavity to the body surface.

Watershed and sinus are semantically related. In some cases you can use "Watershed" instead a noun "Sinus".

Watershed noun - A point in a chain of events at which an important change (as in one's fortunes) occurs.

Sinus and watershed are semantically related. Sometimes you can use "Sinus" instead a noun "Watershed".