thermionic valve

noun

By · According to Wiktionary data (CC BY-SA) ·

"thermionic-valve" is a 15-letter English headword indexed on PlainSpell.

The verdict

“thermionic valve” is uncommon English (outside the top frequency list), classed as a noun. The kind of spelling people second-guess.

Unranked
below top-frequency English
16
letters

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - An electronic device incorporating electrons from a glowing cathode inside an evacuated glass tube, functioning as a switch, amplifier etc.

Key facts for thermionic valve
PropertyValue
Headwordthermionic valve
LanguageEnglish
Part of speechNoun
Letters16
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “thermionic valve” sits in English frequency

thermionic valve falls outside the top-100,000 ranked English words, the long-tail zone of technical, archaic, or low-frequency vocabulary, exactly where readers second-guess spellings most.

Beyond rank #100,000. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

thermionic valve is uncommon English outside the top frequency list, classed as anoun. Rarity is why readers land here mid-draft. Gloss: "An electronic device incorporating electrons from a glowing cathode inside an evacuated glass tube, functioning as a switch, amplifier etc.".

We couldn't generate a plausible misspelling set for thermionic valve, since its letter pattern doesn't lend itself to common typo substitutions. No close-neighbour confusable shows up for this headword in our dataset, which usually means its spelling is distinct enough that readers don't reach for a similar-looking word instead.

Our source data has no etymology on file for this entry, so its spelling is best explained by sound-to-letter mapping rather than etymology. The correct English form is thermionic valve, spelled T-H-E-R-M-I-O-N-I-C- -V-A-L-V-E.

Definition

  1. 1
    An electronic device incorporating electrons from a glowing cathode inside an evacuated glass tube, functioning as a switch, amplifier etc.

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "thermionic valve"?
"thermionic valve" is spelled T-H-E-R-M-I-O-N-I-C- -V-A-L-V-E.
What does "thermionic valve" mean?
As a noun, "thermionic valve" means: An electronic device incorporating electrons from a glowing cathode inside an evacuated glass tube, functioning as a switch, amplifier etc.
What language does "thermionic valve" come from?
"thermionic valve" is a English word. PlainSpell's reference spans five languages -- English, Spanish, Portuguese, French, and German -- with definitions, pronunciations, and spelling data for each.
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.

Using “thermionic valve”

The practical upshot for anyone who landed here from a spell-check.

  • The one correct English spelling is T-H-E-R-M-I-O-N-I-C- -V-A-L-V-E - every other letter order is a misspelling in standard orthography.
  • Browse more English words and confusable pairs in the same reference. English words
Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

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

Source: FrequencyWords open word-frequency list