'intermoult' originates from Latin and Old French: the prefix 'inter-' comes from Latin 'inter' meaning 'between', and 'moult' comes (via Old French 'molt') from Latin 'mutare' meaning 'to change'.

'intermoult' was formed in English by combining the Latin-derived prefix 'inter-' with the word 'moult' (Old French 'molt'); the compound appears in modern English in the form 'intermoult' (also spelled 'intermolt' in US usage).

Initially, the components conveyed 'between changes'; over time this specifically came to mean 'the interval between successive moults' in zoological usage.