cosine
/ˈkəʊ.saɪn/
"cosine" is a 6-letter English headword indexed on PlainSpell.
The verdict
“cosine” is an uncommon English word, ranked #52,240 in English word frequency and used as a noun.
- #52,240
- frequency rank, English
- 6
- letters
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - In a right triangle, the ratio of the length of the side adjacent to an acute angle to the length of the hypotenuse. Symbol: cos
| Property | Value |
|---|---|
| Headword | cosine |
| Language | English |
| Part of speech | Noun |
| IPA | /ˈkəʊ.saɪn/ |
| Letters | 6 |
| Frequency rank | #52,240 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Where “cosine” sits in English frequency
Spelling & Dictionary Insight
The English entry for cosine is 6 letters long, classified as a noun, and transcribed in the International Phonetic Alphabet as /ˈkəʊ.saɪn/. Corpus data places it at rank #52,240 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. The dominant gloss from Wiktionary reads: "In a right triangle, the ratio of the length of the side adjacent to an acute angle to the length of the hypotenuse. Symbol: cos".
cosine has no tracked misspelling variants, suggesting the orthography follows predictable English patterns. This headword has no recorded confusable partner, a sign it's visually distinctive enough not to be mixed up with another word.
Etymologically, the entry records: From co- + sine, short for complementi sinus in Latin, meaning “sine of the complement”. Doublet of cosinus. The correct English form is cosine, spelled C-O-S-I-N-E.
Definition
- 1In a right triangle, the ratio of the length of the side adjacent to an acute angle to the length of the hypotenuse. Symbol: cos
Etymology
From co- + sine, short for complementi sinus in Latin, meaning “sine of the complement”. Doublet of cosinus.
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 "cosine"?
What does "cosine" mean?
How do you pronounce "cosine"?
What is the origin of the word "cosine"?
Is PlainSpell free to use?
Using “cosine”
The practical upshot for anyone who landed here from a spell-check.
- The one correct English spelling is C-O-S-I-N-E - every other letter order is a misspelling in standard orthography.
- Say it as /ˈkəʊ.saɪn/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
- 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.