Oceanid
Concise Oxford English Dictionary © 2008 Oxford University Press:
Oceanid /əʊˈsiːənɪd, ˈəʊʃ(ə)nɪd/
▶noun (pl. Oceanids or Oceanides /ˌəʊsɪˈanɪdiːz, ˌəʊʃɪ-/) Greek Mythology a sea nymph.
– origin from Fr. Océanide, from Gk ōkeanis, ōkeanid-.
'Oceanid' also found in these Oxford entries:

