What does Ianthe mean?
From Greek 'ion' (violet) + 'anthos' (flower), giving 'violet flower'. Borne by a figure in Greek mythology (an Oceanid) and used by Lord Byron. A minority of sources offer alternative roots, but 'violet flower' is the standard etymology.
What does Nerida mean?
Associated with the Greek Nereids, the sea nymphs who were daughters of the sea-god Nereus, and with Greek neros 'water'. The name itself appears to be a relatively modern coinage (a popular Australian claim of an Aboriginal 'water lily' meaning is poorly documented), so treat the sea-nymph sense as its best-supported reading.