Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
forfeit [ˈfɔːfɪt] n (penalty) штраф
vt (right, friendship etc) теря́ть (потеря́ть perf) (one's happiness, health) поплати́ться*(perf) +instr
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.
Русский: