'rarely-kept' originates from the combination of 'rarely,' meaning 'not often,' and 'kept,' the past participle of 'keep,' meaning 'to maintain or preserve.'

'rarely-kept' evolved from the Middle English word 'rarelikept,' which combined 'rarely' and 'kept' to describe something not often maintained.

Initially, it meant 'not often maintained,' and this meaning has largely remained the same in modern usage.