suffocation; choking; asphyxia
death by suffocation; death by choking
nitrogenous fertilizer; nitrogenous fertiliser
nitridization; nitriding; nitride (of)
suffocating; asphyxiating
nitrogen oxide (esp. nitric oxide, but also nitrous oxide, nitrogen dioxide, dinitrogen pentoxide, etc.)
nitrogen fixation (method)
dinitrogen monoxide; nitrous oxide
nitrogen group (group 15 of the periodic table)