Oaths vs Swear

When to use each in English, with meaning, register, and examples.

Oaths

Formal Beyond 10,000 (less common)

Swear

Informal Top 2,000 (common) B2 verb

Most formal: Oaths Most common: Swear

	Oaths	Swear
Pronunciation	🇬🇧 //oʊθs// 🇺🇸 //oʊθs//	🇬🇧 /["/sweə(r)/","/sweəz/","/swɔː(r)/","/swɔːn/","/ˈsweərɪŋ/"]/ 🇺🇸 /["/swer/","/swerz/","/swɔːr/","/swɔːrn/","/ˈswerɪŋ/"]/
Meaning	Formal promises, often made publicly.	To use rude or offensive words.
Example	The witness took several oaths before testifying in court.	I swear to tell the truth in my testimony.
Register	Formal	Informal
How common	Beyond 10,000 (less common)	Top 2,000 (common)
CEFR level	-	B2
Part of speech		verb
Collocations	take an oath, swear oaths, make oaths, honor oaths	loudly, quietly, silently, hear somebody, at, solemnly, on oath, under oath, be prepared to, make somebody, by, on, to, be sworn into office, swear somebody to secrecy, swear somebody to silence, solemnly, on oath, under oath, be prepared to, make somebody, by, on, to, be sworn into office, swear somebody to secrecy, swear somebody to silence, solemnly, on oath, under oath, be prepared to, make somebody, by, on, to, be sworn into office, swear somebody to secrecy, swear somebody to silence, solemnly, on oath, under oath, be prepared to, make somebody, by, on, to, be sworn into office, swear somebody to secrecy, swear somebody to silence
Antonyms	dishonor, break a promise	praise, compliment
Common mistakes	Confused with 'oathes'; the correct plural is 'oaths'., Using 'oath' instead of 'oaths' when referring to multiple promises., Misunderstanding the religious context; not all oaths are religious.	Confusing 'swear' with 'promise' — they have different meanings., Using it in formal writing where it's not acceptable., Using 'swear to' instead of 'swear at' when expressing anger.
Usage notes	Used in official or legal contexts. Avoid in casual conversations. 'Take an oath' is a more common phrase.	Used in informal settings to express anger or frustration. Often considered inappropriate in formal contexts. Be cautious of the audience and setting before using.

See it in real clips

The Lord Of The Rings › The return of the king

Now is the hour. Riders of Rohan, oaths you have taken.

Oaths

I swear. All the guineas are buying it, huh?

How I Met Your Mother › S1 E1

- I swear. - I swear.

I swear. All the guineas are buying it, huh?

How I Met Your Mother › S1 E1

- I swear. - I swear.

Swear

Frequently asked questions: Oaths vs Swear

What's the difference between Oaths and Swear?

Oaths: Formal promises, often made publicly. Swear: To use rude or offensive words.

Which is more formal: Oaths and Swear?

Oaths is the most formal of these.

Which is more common: Oaths and Swear?

Swear is the most common in everyday English.

Can you show an example of each?

Oaths: The witness took several oaths before testifying in court. Swear: I swear to tell the truth in my testimony.

Can I use Oaths and Swear interchangeably?

Not always. Oaths and Swear are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.