'N-phenyl' originates from chemical nomenclature combining the letter 'N' (denoting substitution at nitrogen) and 'phenyl', which was coined in 19th-century organic chemistry to name the radical derived from benzene (from French 'phényle').

'Phenyl' was coined in the 1800s to refer to the radical C6H5 (derived from benzene); later, systematic chemical naming added the prefix 'N-' to indicate attachment at a nitrogen atom, producing the modern term 'N-phenyl'.

Initially, 'phenyl' referred generally to the benzene-derived radical; over time 'N-phenyl' came to be used specifically for a phenyl group attached to nitrogen in a molecule.