'microbic' originates ultimately from Greek via Modern Latin and French, specifically from the word 'microbe' (French 'microbe'), where the prefix 'micro-' meant 'small' and Greek 'bios' meant 'life'.

'microbic' developed from the 19th-century French noun 'microbe' (coined from Greek elements) into English as 'microbe', and then the adjective form 'microbic' was formed in English by adding the suffix '-ic'.

Initially tied to the noun meaning 'small life' (a microbe), it evolved into the adjectival sense 'relating to microbes' used in modern English.