thallus

/ˈθæl.əs/

//ˈθæl.əs// noun

"thallus" is a 7-letter English headword indexed on PlainSpell.

The verdict

“thallus” is uncommon English (frequency #89,988 among 3,151 “T” headwords), classed as a noun. The kind of spelling people second-guess.

#89,988
frequency rank, English
3,151
“T” headwords

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - An undifferentiated plant body, such as in algae.

Corpus desk

Index EN-thallus · thallus · English

thallus · rank #89,988 · 0 variants · 0 confusables

  • FREQ-RARE #89,988
  • LEN-LONG 7 letters
  • VOW-2 2 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-MID 3,151
  • PHOTO-FINISH Theotokos

Nearest frequency peer: Theotokos (+2 rank slots)

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Long-tail ranks near “thallus”

Sparse band: bars invert rank so rarer forms read shorter

corpus weight

What this shows Long-tail view: where “thallus” sits against similarly uncommon English ranks.

Source FrequencyWords open word-frequency list As of September 3, 2026
Key facts for thallus
PropertyValue
Headwordthallus
LanguageEnglish
Part of speechNoun
IPA/ˈθæl.əs/
Letters7
Frequency rank#89,988
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “thallus” in English

This scale runs from the tiny cluster of words that carry ordinary speech (left) to the long tail of words almost nobody reaches for (right).thallusfalls in this rarity band:

#1#100#1K#10K#100K
← used constantlyrarely used →

Ticks step logarithmically, so each one marks a roughly tenfold drop in how often the word turns up. Rare peers in the same band: “Theotokos” (#89,990), “thoracotomy” (#89,991), “Tenzing” (#89,983). Among 3,151 “T” headwords, “thallus” is #89,988. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

thallus is uncommon English at frequency #89,988 among 3,151 “T” headwords, classed as anoun, transcribed /ˈθæl.əs/. Rarity is why readers land here mid-draft. 2 senses are on record.

Zero misspellings are on record for thallus in our index, since its letter pattern doesn't lend itself to common typo substitutions. No close-neighbour confusable shows up for this headword in our dataset, since no other headword is close enough in sound or shape to pair with it.

Etymologically, the entry records: From Ancient Greek θαλλός (thallós, “young shoot, twig”), from Proto-Indo-European *dʰelh₁- (“to bloom”). The correct English form is thallus, spelled T-H-A-L-L-U-S.

Definition

  1. 1
    An undifferentiated plant body, such as in algae.
  2. 2
    Any plant body lacking vascular tissue.

Recorded use

Wiktionary example

These source excerpts show how thallus appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. As it flows it takes the forms of sappy leaves or vines, making heaps of pulpy sprays a foot or more in depth, and resembling, as you look down on them, the laciniated, lobed, and imbricated thalluses of some lichens; […]

Etymology

From Ancient Greek θαλλός (thallós, “young shoot, twig”), from Proto-Indo-European *dʰelh₁- (“to bloom”).

This word in other languages

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "thallus"?
"thallus" is spelled T-H-A-L-L-U-S. The IPA pronunciation is /ˈθæl.əs/.
What does "thallus" mean?
As a noun, "thallus" means: An undifferentiated plant body, such as in algae.
How do you pronounce "thallus"?
The IPA (International Phonetic Alphabet) transcription for "thallus" is /ˈθæl.əs/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "thallus"?
From Ancient Greek θαλλός (thallós, “young shoot, twig”), from Proto-Indo-European *dʰelh₁- (“to bloom”). See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "thallus", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 7 letters (nearest by frequency rank).

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list