zoo-

1.
a combining form meaning “living being,” “animal,” used in the formation of compound words:
zoometry; zooplankton.
Also, especially before a vowel, zo-.
Origin
combining form representing Greek zôion animal
British Dictionary definitions for zoo-

zoo-

combining form
1.
indicating animals: zooplankton
Word Origin
from Greek zōion animal
zoo- in Medicine

zoo- or zo-
pref.
Animal; animal kingdom: zoonosis.