compulsory

The word 'compulsory' originates from the late Latin term compulsorius, which itself derives from the past participle stem compuls- of the verb compellere, meaning 'to drive together, force, compel'. The root pellere (to drive) is of Proto-Indo-European origin, related to concepts of striking and propulsion. The semantic journey moved from the literal sense of physically driving or forcing someone, to the legal and social concept of an action that is mandated and unavoidable. Thus, the modern meaning of 'required by authority' logically extends from the ancient idea of being driven or compelled by an external force.

Structure: com (together) + puls (drive) + ory (adjective suffix) com- (Latin prefix meaning 'together, with'), puls- (from Latin pellere, 'to drive'), -ory (Latin adjectival suffix meaning 'pertaining to, serving for').