'momentarily-kept' originates from the combination of 'momentarily' and 'kept', where 'momentarily' is derived from 'moment', meaning 'a brief period of time', and 'kept' is the past participle of 'keep', meaning 'to hold or retain'.

'momentarily' changed from the Old French word 'moment', and 'kept' evolved from the Old English word 'cepan', eventually forming the modern English term 'momentarily-kept'.

Initially, 'momentarily' meant 'for a moment', and 'kept' meant 'held', but together they evolved to mean 'held for a short time'.