Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
frighten [ˈfraɪtn] vt пуга́ть (испуга́ть or напуга́ть perf)
frighten away vt (birds, children etc) спу́гивать (спугну́ть perf)
frighten off vt = frighten away
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.