Lewis & Short

2. rĕpulsus, ūs, m. [repello], a driving back, repulsion, rebounding, reflection, reverberation (of light, sound, etc.; poet.; usually in abl. sing.): (effigies) assiduo crebroque repulsu Rejectae, Lucr. 4, 106: lucis, Claud. Cons. Mall. Theod. 106: stridor adaugescit scopulorum saepe repulsu, reechoing, Cic. poët. Div. 1, 7, 13: repulsus raucos umbonum, Claud. B. Gild. 433: dentium, i. e. the striking together, Plin. 11, 37, 62, § 164: durioris materiae, resistance, id. 8, 43, 68, § 169.