An English plural form of craninium (now obsolete), referring to the bony case that encloses the brain.
Craninium comes from Greek 'kranion.' Using -iums as an English plural shows how English sometimes Anglicizes Latin scientific terms rather than using Latin plurals.
This is a word caught between languages—Latin wanted 'crania,' but English speakers said 'craniniums,' creating a word so awkward it completely disappeared from modern use.
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