- The definition of a hectocotylus is a specific arm of a cephalopod that transfers sperm to the female.
An example of hectocotylus is what a male octopus uses to get a female octopus pregnant.
Origin: ModL from hecto- plush Glassical Greek kotylē, a hollow, cavity
Used by arrangement with John Wiley & Sons, Inc.
noun pl. hec·to·cot·y·li
Origin: New Latin : hecto- + Greek kotulē, small cup.