sick as a dog

adj

"sick-as-a-dog" is a 10-letter English headword indexed on PlainSpell.

The verdict

“sick as a dog” is uncommon English (outside the top frequency list), classed as an adjective. The kind of spelling people second-guess.

Unranked
below top-frequency English
13
letters

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Very ill.

Corpus desk

Index EN-sick-as-a-dog · sick as a dog · English

sick as a dog · unranked · 0 variants · 0 confusables

  • FREQ-UNRANKED Unranked
  • LEN-MEGA 13 letters
  • VOW-4 4 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-THIN "S" thin
  • PHOTO-UNK Peer pending

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.

Key facts for sick as a dog
PropertyValue
Headwordsick as a dog
LanguageEnglish
Part of speechAdjective
Letters13
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “sick as a dog” in English

sick as a dogsits beyond the 100,000 most-frequent English words, in the long tail of technical, archaic, or otherwise rare vocabulary where spelling doubt tends to strike hardest.

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

Rare enough to double-check

sick as a dog is uncommon English outside the top frequency list, classed as anadjective. Rarity is why readers land here mid-draft. Gloss: "Very ill.".

No generated misspelling entries exist for sick as a dog in our index, which points to an orthography that plays by predictable English rules. No confusable counterpart is on file for this word, since its spelling is unusual enough that it doesn't cluster with a lookalike.

This entry carries no recorded etymology, so its spelling is easiest explained by how it's pronounced rather than where it came from. The correct English form is sick as a dog, spelled S-I-C-K- -A-S- -A- -D-O-G.

Definition

  1. 1
    Very ill.

Recorded use

Wiktionary examples

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

  1. I caught that new strain of flu and for three days I was as sick as a dog.
  2. Ay, but thou knowest he's as uncertain as the wind; and if, instead of quarrelling with me, he should grow fond, he'd make me as sick as a dog.

Synonyms

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). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "sick as a dog"?
"sick as a dog" is spelled S-I-C-K- -A-S- -A- -D-O-G.
What does "sick as a dog" mean?
As an adjective, "sick as a dog" means: Very ill.
What language does "sick as a dog" come from?
"sick as a dog" 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.

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

Source: FrequencyWords open word-frequency list