n. The ethical study of duties, obligations, and rights, with an approach focusing on the rightness or wrongness of actions themselves and not on the goodness or badness of the consequences of those actions.
the GNU version of the Collaborative International Dictionary of English
n. The science which relates to duty or moral obligation.
The Century Dictionary and Cyclopedia
n. The science of duty; ethics.
Word Usage
"The term deontology is derived from the Greek deon which means binding duty."