'tailor' originates from Old French, specifically the word 'tailleur' (one who cuts), ultimately from Late Latin 'taliare' meaning 'to cut'.

'taliare' (Late Latin) > Old French 'tailleur'/'taillour' > Middle English 'taillour' > modern English 'tailor' (and adjectival form 'tailored' derived from the verb).

Initially it meant 'to cut' or 'one who cuts'; over time it came to mean 'one who makes or alters garments' and further extended to 'adapt or modify (something) for a particular purpose', which is how 'tailored' is used today.