British spelling: to treat, coat, or impregnate something with bitumen.
From 'bitumen' plus the British suffix '-ise' (American '-ize'). Both spellings follow the pattern of Latin-derived verbs in English that received '-ize/-ise' suffixes starting in the 14th century.
In British English, engineers 'bituminise' roads, while American engineers 'bituminize' them—same process, different spelling traditions reflecting the split between British and American English!
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