'unexpectedly-stopping' is a compound word formed from 'unexpectedly' and 'stopping'. 'Unexpectedly' originates from the Latin word 'exspectare', meaning 'to look out for', and 'stopping' comes from the Old English 'stoppian', meaning 'to block or close'.

'Unexpectedly' evolved from the Latin 'exspectare' through Old French 'expecter', while 'stopping' evolved from Old English 'stoppian'.

Initially, 'unexpectedly' meant 'not looked for', and 'stopping' meant 'to block'. Over time, they combined to describe an action that halts without prior notice.