thallo-

thallo-

or thall-
pref.
1.
a. Young, green shoot: thallium.
b. Thallus: thalloid.
2. Thallium: thallous.

[Greek, from thallos; see thallus.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.