Oaths vs Promise

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

Oaths

Formal Beyond 10,000 (less common)

Promise

Top 1,000 (very common) A2 verb

Most formal: Oaths Most common: Promise

	Oaths	Promise
Pronunciation	🇬🇧 //oʊθs// 🇺🇸 //oʊθs//	🇬🇧 /["/ˈprɒmɪs/","/ˈprɒmɪsɪz/","/ˈprɒmɪst/","/ˈprɒmɪsɪŋ/"]/ 🇺🇸 /["/ˈprɑːmɪs/","/ˈprɑːmɪsɪz/","/ˈprɑːmɪst/","/ˈprɑːmɪsɪŋ/"]/
Meaning	Formal promises, often made publicly.	A commitment to do something or not do something.
Example	The witness took several oaths before testifying in court.	I promise to help you with your homework.
Register	Formal	Neutral
How common	Beyond 10,000 (less common)	Top 1,000 (very common)
CEFR level	-	A2
Part of speech		verb
Collocations	take an oath, swear oaths, make oaths, honor oaths	faithfully, solemnly, initially, can, cannot, seem to, to, as promised, I can’t promise anything
Antonyms	dishonor, break a promise	lie, break, betray
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 'promise' with 'vow' or 'pledge' in terms of strength., Using 'promise' without an object (e.g., 'I promise' should specify what)., Misusing in the past tense (e.g., 'I promised' without a follow-up).
Usage notes	Used in official or legal contexts. Avoid in casual conversations. 'Take an oath' is a more common phrase.	Use 'promise' when you want to express a vow or assurance. Common in both spoken and written contexts, but avoid in formal legal documents.

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

And one system shows promise.

and I always try to keep my promise.

And one system shows promise.

and I always try to keep my promise.

Promise

Frequently asked questions: Oaths vs Promise

What's the difference between Oaths and Promise?

Oaths: Formal promises, often made publicly. Promise: A commitment to do something or not do something.

Which is more formal: Oaths and Promise?

Oaths is the most formal of these.

Which is more common: Oaths and Promise?

Promise is the most common in everyday English.

Can you show an example of each?

Oaths: The witness took several oaths before testifying in court. Promise: I promise to help you with your homework.

Can I use Oaths and Promise interchangeably?

Not always. Oaths and Promise 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.