the GNU version of the Collaborative International Dictionary of English
n. One who engages or undertakes; a promiser.
The Century Dictionary and Cyclopedia
n. In law, one who promises.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a person who makes a promise
Word Usage
"The only universal consequence of a legally binding promise is, that the law makes the promisor pay damages if the promised event does not come to pass."