An Etymological Dictionary of Astronomy and Astrophysics

The action or state of forcing or being forced to do something; constraint (OxforddDctionaries.com).

Etymology (EN): M.E., from O.Fr. compulsion, from L. compulsion-, noun of action from past-participle stem of compellere, → compel.

Etymology (PE): Verbal noun from vâdâridan, vâdâr kardan, → compel.