'avertible' originates from Latin, specifically the word 'avertere' (also written 'avertĕre'), where the prefix 'ab-/a-' meant 'away' and the root 'vertere' meant 'to turn', combined with the suffix '-ible' from Latin '-ibilis' meaning 'able to'.

'avertible' changed from the Latin verb 'avertere' to Old French forms (e.g. 'avertir') and Middle English (e.g. 'averten'/'avert'), with the adjectival suffix '-ible' (from Latin via Old French) producing the modern English adjective 'avertible'.

Initially it meant 'able to be turned away' (literally 'able to be turned away from'), and over time it evolved into the current sense 'able to be prevented' or 'avoidable'.