'amenorrhoeal' originates from Greek, specifically the word 'amenorrhoia,' where 'a-' meant 'without,' 'men' meant 'month,' and 'rhoia' meant 'flow.'

'amenorrhoia' transformed into the modern English word 'amenorrhea' and its adjective form 'amenorrhoeal.'

Initially, it meant 'without monthly flow,' and this meaning has largely remained the same in modern usage.