<p><strong>Verb:</strong></p><ul><li>To oxidize (ammonia, ammonium compounds, or free atmospheric nitrogen) to nitrites and then to nitrates, especially in soil by bacterial or other microbial action.</li><li>To infuse with nitrogen or nitrogen compounds.</li><li>To treat or combine with nitrogen or its compounds.</li><li>(Formerly) to convert into niter.</li><li>Nitriﬁed, nitriﬁying.</li></ul>