'economy-sized' is a Modern English compound formed from the noun 'economy' and the noun 'size' with the adjectival suffix '-ed'. 'economy' originates from Greek, specifically the word 'oikonomia', where 'oikos' meant 'house' and 'nomos' meant 'management'; 'size' originates from Old French, specifically the word 'sise', where it referred to a fixed measure or quantity.

'oikonomia' passed into Latin as 'oeconomia', then through Old French and Middle English to become the modern English word 'economy'. Old French 'sise' (or similar forms) evolved into Middle English 'size'. In Modern English these elements combined with the adjectival '-ed' to form 'economy-sized'.

Initially, 'economy' meant 'household management' and 'size' meant 'a measure or quantity'; over time, combined usage produced the adjective 'economy-sized', meaning 'a larger quantity sold or packaged to reduce cost per unit'.