Lewis & Short

2. cŏactus, ūs, m. [cogo], a forcing, constraint, compulsion (rare and only in abl. sing.): alterius magno coactu, * Lucr. 2, 273: coactu atque efflagitatu meo, Cic. Verr. 2, 5, 29, § 75; 2, 2, 13, § 34: civitatis, Caes. B. G. 5, 27.