Pronunciation: (nī'tru-fī"),[key] —v.t.,-fied, -fy•ing. 1. to oxidize (ammonia, ammonium compounds, or atmospheric nitrogen) to nitrites, nitrates, or their respective acids, esp. by bacterial action.
2. to impregnate with nitrogen or nitrogen compounds.
3. to treat or combine with nitrogen or its compounds.
4. (formerly) to convert into niter.