'rarely-expressed' originates from the combination of 'rarely,' meaning 'not often,' and 'expressed,' meaning 'articulated or communicated.'

'Rarely' and 'expressed' have been used in English since the Middle Ages, but the compound form 'rarely-expressed' is a modern construction.

Initially, 'rarely' meant 'seldom' and 'expressed' meant 'articulated,' and this meaning has largely remained the same in modern usage.