hectocotylus

noun, plural hec·to·cot·y·li [hek-tuh–kot-l-ahy] /ˌhɛk təˈkɒt lˌaɪ/. Zoology.

1. a modified arm of the male of certain cephalopods that is used to transfer sperm to the female.

noun plural -li (-ˌlaɪ)

1. a tentacle in certain male cephalopod molluscs, such as the octopus, that is specialized for transferring spermatozoa to the female