lightspeed

noun

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

"lightspeed" is a 10-letter English headword indexed on PlainSpell.

The verdict

“lightspeed” is uncommon English (frequency #61,593 among 16,425 “L” headwords), classed as a noun. The kind of spelling people second-guess.

#61,593
frequency rank, English
16,425
“L” headwords

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - The speed of light (in vacuum unless another medium is specified).

Key facts for lightspeed
PropertyValue
Headwordlightspeed
LanguageEnglish
Part of speechNoun
Letters10
Frequency rank#61,593
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “lightspeed” sits in English frequency

Every-word frequency runs from the handful of words we use constantly (left) to the long tail used once in a blue moon (right). lightspeed lands here:

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

Scale is logarithmic (each tick is 10× rarer). Source: FrequencyWords open word-frequency list.

Rare enough to double-check

lightspeed is uncommon English at frequency #61,593 among 16,425 “L” headwords, classed as anoun. Rarity is why readers land here mid-draft. 2 senses are on record.

The misspelling generator found no plausible variants for lightspeed, since its letter pattern doesn't lend itself to common typo substitutions. No confusable counterpart is on file for this word, a sign it's visually distinctive enough not to be mixed up with another word.

Etymologically, the entry records: From light + speed. The correct English form is lightspeed, spelled L-I-G-H-T-S-P-E-E-D.

Definition

  1. 1
    The speed of light (in vacuum unless another medium is specified).
  2. 2
    An extremely fast speed.

Etymology

From light + speed.

This word in other languages

velocidad de la luz(Español)vitesse de la lumière(Français)Lichtgeschwindigkeit(Deutsch)

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 "lightspeed"?
"lightspeed" is spelled L-I-G-H-T-S-P-E-E-D.
What does "lightspeed" mean?
As a noun, "lightspeed" means: The speed of light (in vacuum unless another medium is specified).
What is the origin of the word "lightspeed"?
From light + speed. 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.

Using “lightspeed”

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

  • The one correct English spelling is L-I-G-H-T-S-P-E-E-D - every other letter order is a misspelling in standard orthography.
  • Browse more English words and confusable pairs in the same reference. English words

Other uncommon English words near this rank

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 FrequencyWords open word-frequency list