'predivided' is formed in Modern English from the prefix 'pre-' (from Latin 'prae' meaning 'before') and the verb 'divide' (from Latin 'dividere' meaning 'to separate').

'divide' entered English via Old French and Middle English (Old French 'divider' / Medieval Latin 'dividere'), ultimately from Latin 'dividere'; the productive prefix 'pre-' (Latin 'prae') has been combined with verbs in Modern English to form compounds like 'predivide' and its past form 'predivided'.

Originally 'divide' meant 'to separate into parts'; with the prefix 'pre-' the compound came to mean 'to separate into parts beforehand' and this specific temporal nuance ('beforehand') is the primary sense of 'predivided'.