'seldom-mentioned' originates from the combination of 'seldom' and 'mentioned', where 'seldom' comes from Old English 'seldan', meaning 'rarely', and 'mentioned' is derived from Latin 'mentio', meaning 'a calling to mind'.

'seldan' transformed into Middle English 'seldom', and 'mentio' evolved into the modern English 'mention'.

Initially, 'seldom' meant 'rarely', and 'mention' meant 'to call to mind'. The combination retains the original meanings, indicating something rarely brought up.