'obligatorily-assembled' originates from the combination of 'obligatory' and 'assembled', where 'obligatory' comes from Latin 'obligatorius', meaning 'binding', and 'assembled' from Old French 'assembler', meaning 'to gather'.

'obligatorily' evolved from the Latin 'obligatorius', and 'assembled' from Old French 'assembler', eventually forming the modern English term 'obligatorily-assembled'.

Initially, 'obligatory' meant 'binding or compulsory', and 'assembled' meant 'gathered or put together'. The combined term retains these meanings, emphasizing the necessity of assembly.