Avow
"promise to obey"
vow
The definition of the word vow is a solemn promise or dedication to something.
To "give your word" means to promise.
oath
vow
It means it's a promise. The same as "I promise you."
commit, pledge
oath
Owe, IOU
Breaking a Promise
The first letter of the six-letter word that means to go back on a promise is "R," which stands for "reneged."