'thiazolyl' originates from New Latin/chemical nomenclature, specifically the word 'thiazole' plus the suffix '-yl', where 'thio-' meant 'sulfur', 'azole' referred to 'a class of nitrogen-containing heterocycles', and '-yl' denoted 'a radical or substituent'.

'thiazolyl' changed from the base name 'thiazole' (coined in the 19th century from Greek/chemical roots) combined with the organic-chemistry suffix '-yl', and eventually became the established modern term 'thiazolyl' used to indicate a thiazole-derived substituent.

Initially, the formation indicated 'a radical derived from thiazole', and over time this has remained the current meaning: 'a thiazole-derived substituent or relating to such a substituent'.