Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
field [fiːld] n (also ELEC, COMPUT) по́ле; (SPORT) по́ле, площа́дка# (fig, area of interest) о́бласть*f
cpd (study, trip, scientist etc) полево́й
the field (competitors, entrants) уча́стники mpl состяза́ния
they lead the field (COMM) они́ веду́щие в свое́й о́бласти
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.