Full of or characterized by cleaving; tending to split or separate readily.
From 'cleave' (to split) plus '-ful' suffix meaning full of. This is an archaic or rare formation that combines the root verb with a productivity suffix to create an descriptive adjective.
While 'cleaveful' is rarely used in modern English, it shows how Old English speakers would describe naturally brittle materials by combining common word-building pieces—it's like how we might say 'splinter-full' for wood that breaks easily.
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