chaplain

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A member of the clergy attached to a chapel.
• noun A member of the clergy who conducts religious services for an institution, such as a prison or hospital.
• noun A lay person who is appointed to provide spiritual leadership and counseling to members of an institution, as at a university.
• noun A member of the clergy who is connected with a royal court or an aristocratic household.
• noun A member of the clergy attached to a branch of the armed forces.

from The Century Dictionary.

• noun An ecclesiastic attached to a chapel; especially, one officiating in the private chapel of a king or nobleman, or other person of wealth or distinction.
• noun An ecclesiastic who renders service to one authorized to employ such assistance, as to an archbishop, or to a family; a confessor.
• noun A clergyman who occupies an official position, and performs certain religious functions, in the army or navy, in a legislative or other public body, in a charitable institution, or the like: as, the chaplain of the House of Representatives.
• noun A private secretary to the lady superior of a convent.

from the GNU version of the Collaborative International Dictionary of English.

• noun An ecclesiastic who has a chapel, or who performs religious service in a chapel.
• noun A clergyman who is officially attached to the army or navy, to some public institution, or to a family or court, for the purpose of performing divine service.
• noun Any person (clergyman or layman) chosen to conduct religious exercises for a society, etc..

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A member of the clergy officially assigned to an institution, group, private chapel, etc.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a clergyman ministering to some institution