Nitro-

Part of speech: noun (n.)

1. A combining form or an adjective denoting the presence of niter.

2. A combining form (used also adjectively) designating certain compounds of nitrogen or of its acids, as nitrohydrochloric, nitrocalcite; also, designating the group or radical NO2, or its compounds, as nitrobenzene. Nitro group, the radical NO2; -- called also nitroxyl.