[ thal-uhs ]
/ ˈθæl əs /
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noun, plural thal·li [thal-ahy], /ˈθæl aɪ/, thal·lus·es.Botany, Mycology.
a simple vegetative body undifferentiated into true leaves, stem, and root, ranging from an aggregation of filaments to a complex plantlike form.
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Origin of thallus

1820–30; <New Latin <Greek thallós young shoot, twig
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use thallus in a sentence

British Dictionary definitions for thallus

/ (ˈθæləs) /

noun plural thalli (ˈθælaɪ) or thalluses
the undifferentiated vegetative body of algae, fungi, and lichens

Derived forms of thallus

thalloid, adjective

Word Origin for thallus

C19: from Latin, from Greek thallos green shoot, from thallein to bloom
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for thallus

[ thăləs ]

Plural thalli (thălī)
A type of body found among plants and fungi that is not differentiated into roots, stems, or leaves. Thalli are found among lichens, mosses, liverworts, and many algae, as well as the gametophyte generations of horsetails and ferns, which have rhizoids but not true roots.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.