'isosepalous' originates from New Latin, specifically the word 'isosepalus', where the prefix 'iso-' meant 'equal' and 'sepalum' meant 'sepal'.

'isosepalous' changed from the New Latin form 'isosepalus' and was adopted into botanical English usage in the 19th century, eventually becoming the modern English word 'isosepalous'.

Initially, it meant 'having equal sepals', and this meaning has largely remained the same in modern usage.