SINCE 1828

An Encyclopædia Britannica Company

thallus

play

noun thal·lus \ ˈtha-ləs \

Definition of thallus

plural thalli play \ˈtha-ˌlī, -ˌlē\ or thalluses

:a plantlike vegetative body (as of algae, fungi, or mosses) that lacks differentiation into distinct parts (such as stem, leaves, and roots) and does not grow from an apical point

Origin and Etymology of thallus

New Latin, from Greek thallos, from thallein to sprout; akin to Armenian dalar green, fresh, Albanian dal I come forth

NEW! Time Traveler

First Known Use: 1829

See Words from the same year

Medical Dictionary

thallus

play

noun thal·lus \ ˈthal-əs \

medical Definition of thallus

plural thalli play \ˈthal-ˌī, -ˌē\ or thalluses

:a plant or plantlike body (as of an alga, fungus, or moss) that lacks differentiation into distinct members (as stem, leaves, and roots) and does not grow from an apical point

Learn More about thallus

See words that rhyme with thallus Britannica.com: Encyclopedia article about thallus

Seen and Heard

What made you want to look up thallus? Please tell us where you read or heard it (including the quote, if possible).

show

WORD OF THE DAY

holus-bolus

play

all at once

BROWSE DICTIONARY

thallose

thallous

thallus

thalposis

thalpotic

Test Your Vocabulary

Challenging Vocabulary Quiz Returns!

Which is a synonym of fuliginous?

Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ

SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Words at Play

alt-59c17b8172892

'So Long': A Common But Mysterious Goodbye

Its origins are surprisingly murky.

alt-59c13729150dc

"Immune to" or "Immune from"?

Nobody is immune to this question.

alt-59bff395cf879

What's Going On With 'Nonplussed'?

Its recent usage is hard to shrug off.

alt-59bad350d88f1

Welcome to the New Words

From 'hive mind' to 'sriracha'

Ask the Editors

video-title-words-of-the-year-1066

Words of the Year: 1066

Or, Why Pig Meat is Called 'Pork' and Cow Meat is Called 'Beef'

How Often Is 'Biweekly'?

Don't get us started on 'bimonthly'

video-irregardless-grammar-peeve-blend-of-the-synonyms-irrespective-and-regardless

Irregardless

It is in fact a real word (but that doesn't mean you should use it).

video-moose-goose-weird-plurals

Weird Plurals

One goose, two geese. One moose, two... moose. What's up with that?

Word Games

stylized-drawing-of-woman-pole-vaulting-across-gap-to-get-trophy

Challenging Vocabulary Quiz Returns!

No tricks, just difficult words.

Take the quiz

Name that Color!

NEW! Additional colors! More obscure than before!

Take the quiz

Name That Thing

Name That Thing

Test your visual vocabulary with our 10-question challenge!

Take the quiz

SCRABBLE® Sprint

SCRABBLE® Sprint

SCRABBLE® fans, sharpen your skills!

Play the game