'chimeric' originates from New Latin/Modern Latin 'chimericus', ultimately from Greek, specifically the word 'chimaira' (Greek χίμαιρα), where 'chimaira' referred to a mythic creature often described as a composite beast (and originally could mean 'she-goat').

'chimeric' changed from the Greek word 'khimaira' to Latin 'chimera' (the mythological creature), then to New/Modern Latin 'chimericus', and finally entered English as the adjective 'chimeric'.

Initially, it referred specifically to the mythic beast (and etymologically to 'she-goat'); over time it broadened to mean 'composed of disparate parts' and later acquired specialized biological senses (organisms containing genetically distinct cells) and figurative senses (illusory, fanciful).