'premeasured' originates from Latin and Old French elements: the prefix 'pre-' (from Latin 'prae-') meaning 'before', combined with 'measure', which ultimately comes via Old French 'mesurer' from Latin 'mensurare' (related to 'mensura', meaning 'a measuring').

'pre-' (from Latin 'prae-') + Middle English/French 'measure' (from Old French 'mesurer', from Latin 'mensurare') combined in Early Modern English as the compound 'pre-measure' and later formed the past-participle/adjectival 'premeasured'.

Initially the roots meant 'before' and 'to measure'; over time the compound came to be used adjectivally to mean 'measured beforehand' or to describe portions already measured.