1.
vow, oath, pledge, promise
A solemn promise or commitment, often made with deep personal conviction or in a formal ceremonial context. Carries more weight and formality than a simple promise.
Usage
誓い is the noun form of 誓う (to swear, to vow). It carries a solemn, weighty tone — stronger than 約束 (promise). Common contexts include wedding vows, oaths of office, and personal resolutions. The phrase 誓いの言葉 (words of pledge) is used at ceremonies. It is a homophone of 近い (near), which has a completely different meaning.