subdomain

noun

"subdomain" is a 9-letter English headword indexed on PlainSpell.

The verdict

“subdomain” is uncommon English (frequency #86,804 among 54,294 “S” headwords), classed as a noun. The kind of spelling people second-guess.

#86,804
frequency rank, English
54,294
“S” headwords

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - A domain or sphere that is part of a larger domain or sphere.

Key facts for subdomain
PropertyValue
Headwordsubdomain
LanguageEnglish
Part of speechNoun
Letters9
Frequency rank#86,804
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “subdomain” 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). subdomain 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

subdomain is uncommon English at frequency #86,804 among 54,294 “S” headwords, classed as anoun. Rarity is why readers land here mid-draft. 3 senses are on record.

Zero misspellings are on record for subdomain in our index, and the word's spelling is regular enough that our generator found nothing worth flagging. This entry stands alone in our confusable dataset, which usually means its spelling is distinct enough that readers don't reach for a similar-looking word instead.

Etymologically, the entry records: From sub- + domain. The correct English form is subdomain, spelled S-U-B-D-O-M-A-I-N.

Definition

  1. 1
    A domain or sphere that is part of a larger domain or sphere.
  2. 2
    A domain name that has been prefaced with additional parts separated with periods.
  3. 3
    An additional part prefaced to a domain name.

Etymology

From sub- + domain.

Synonyms

unqualified hostname

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 "subdomain"?
"subdomain" is spelled S-U-B-D-O-M-A-I-N.
What does "subdomain" mean?
As a noun, "subdomain" means: A domain or sphere that is part of a larger domain or sphere.
What is the origin of the word "subdomain"?
From sub- + domain. 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 “subdomain”

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

  • The one correct English spelling is S-U-B-D-O-M-A-I-N - 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