[ ek-tuh-zoh-on, -uh n ]
/ ˌɛk təˈzoʊ ɒn, -ən /

noun, plural ec·to·zo·a [ek-tuh-zoh-uh] /ˌɛk təˈzoʊ ə/. Biology.

any animal parasite, as the louse, that lives on the surface of its host (opposed to entozoon).
Also ectozoan.

Origin of ectozoon

First recorded in 1855–60; ecto- + -zoon Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Medicine definitions for ectozoon

[ ĕk′tə-zōŏn′ ]

n. pl. ec•to•zo•a (-zōə)

An animal parasite, such as a flea or louse, living on the exterior of the host organism.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.