'Britain-like' originates from the noun 'Britain' and the adjectival suffix '-like'. 'Britain' ultimately comes from Latin 'Britannia' and earlier Celtic (e.g. Welsh) 'Pritani', while the suffix '-like' comes from Old English 'līc' (also seen as '-lic') meaning 'like' or 'similar'.

'Britain' changed from Latin 'Britannia' (used by the Romans for the island) and earlier Celtic names for the inhabitants; the English form developed through Old English. The suffix '-like' evolved from Old English 'līc'/'-lic' and was productively combined with nouns to form adjectives (e.g. 'child-like'). Together they formed the compound adjective 'Britain-like' in modern English.

Initially the components meant 'the island/people called Britain' and 'similar' respectively; combined, they have consistently meant 'similar to Britain' or 'having qualities of Britain' with little change in core meaning.