ctenidium
Concise Oxford English Dictionary © 2008 Oxford University Press:
ctenidium /tɪˈnɪdɪəm/
▶noun (pl. ctenidia /-dɪə/) Zoology a comb-like respiratory organ in a mollusc.
– origin mod. L., from Gk ktenidion, dimin. of kteis, kten- ‘comb’.
'ctenidium' also found in these Oxford entries:

