The Collaborative International Dictionary
nitro group
Nitroxyl \Ni*trox"yl\, n. [Nitro- + oxygen + -yl.] (Chem.) The group -NO2, usually called the nitro group.
WordNet
nitro group
n. the group -NO3
Usage examples of "nitro group".
The presence of a nitro group (-NO2) in addition has not yet been confirmed, and no evidence as yet exists as to the nature of the hydrocarbon nucleus, though an at least partly aromatic structure seems certain.