The research aims to identify semantic (semasiological and onomasiological) properties of substandard nomination of colour items in New Zealand prison jargon. It is noted that colour terms are differentiated into analogues (lexico-semantic variants of literary lexemes) and univerbs (autonomous nominative units) in the semasiological aspect; the concepts connected with drug use and denoting a person’s racial, ethnic and subcultural background act as synonymic attraction centres. It is emphasised that the excessive variation in the sociolect leading to expressivity and caused by the presence of colour terms as well is considered to be its distinctive feature. The work is novel in that it is the first to describe the semantic properties of New Zealand penitentiary sociolectisms functioning as colour terms, which have been little studied in Russian Anglistics, in the context of sociolexicography. The results obtained during the sociolexicographic analysis have shown that (1) semasiological characteristics peculiar to the elements under study are manifested in the nature of their semantic relation with literary equivalents and in the expansion through them of synonymic rows of the sociolect, (2) onomasiological particular qualities of colour lexemes are realised by means of such mechanisms of semantic derivation as metaphorisation and metonymisation.