2 notes June 29, 2012 ecto- Etymology From the Ancient Greek ἐκτός (ektos, “outside”). Prefix ecto- outside Related terms ectocommensal ectoderm ectogenous ectomere ectomorph ectomorphic ectoparasite ectopia ectopic ectoplasm ectosarc ectotherm ectothermic Filed under biology outside ecto prefix words Etymology