pasteur

Inherited from Middle French pasteur, from Old French pastur, pastor, an accusative form corresponding originally to nominative pastre (whence modern pâtre), from Latin pastor, pastōrem. Early on was there a tendency towards functional split, the original accusative being influenced by the Latin etymon and used particularly in religious context. This influence also explains the survival of the /s/ (instead of *pâteur). A strict division between inherited form and learned use is hardly possible,