'azophenyl' is a modern chemical coinage formed from the combining form 'azo-' (relating to the azo group, from French 'azote' historically used for nitrogen) and 'phenyl' (the phenyl radical name used in organic chemistry).

'Azophenyl' has been used as a trivial or structural name in organic chemistry; earlier systematic terminology for the same structural fragment included 'phenyldiazenyl' (literally 'phenyl–N=N–').

Originally used to denote specifically the radical or substituent derived from azobenzene, it now commonly refers to that substituent group in a range of compounds and contexts.