-or; -our (primarily British)

(Latin: a suffix; state of, result of; he who, that which)

A suffix that forms nouns. British spelling is usually -our.
abdicator (s) (noun), abdicators (pl)
1. Someone who gives up a high office, formally or officially; especially, a royal throne: The duke, by giving up his title, was seen by many as an abdicator.
2. Anyone who fails to fulfill a duty or responsibility: The manager of the store lost his position because he was accused of being an abdicator of his duties.
abductor (s) (noun), abductors (pl)
1. Someone who illegally leads, or takes, another person away by force or deception: The description of the abductor matched the profile in the police station.
2. A muscle that pulls the body or a limb away from a midpoint or midline; such as, raising the arm out from the side: Eric strained both abductors in his right arm when he tried to throw the baseball.
ablator (s) (noun), ablators (pl)
1. The heat shields of space vehicles, which melt or wear away during the reentry into the earth's atmosphere: The scientist created a new ablator which could withstand extreme heat.
2. The outer surface of a spacecraft or missile: Ablation is the erosion of the protective outer surface, or ablator, of a spacecraft or missile resulting from aerodynamic heating caused by travel at hypersonic speeds during reentry through the atmosphere.

The ablators on the spacecraft were welded into place using a specialized metal that would withstand great heat.

acanthor
accelerator (s), accelerators (pl) (nouns
1. A pedal or other device to make something go faster, to speed up, or to quicken the pace: The car suddenly lunged into a tree when Jeremy stepped too hard on the accelerator.
2. A machine used to increase the velocity, and hence the kinetic energy, of subatomic particles or nuclei; usually, in preparation for collision with a target.
adductor (s) (noun), adductors (pl)
A muscle that draws any limb, or part of the body, towards the trunk or main axis, or which folds or closes extended parts of the body.
adjutor
A helper or assistant.
aerator (s) (noun), aerators (pl)
1. A device used to circulate air in a substance or medium; such as, to expose it to air or another gas.
2. Specifically, a device installed in a faucet or showerhead to add air to the water flow; thus, maintaining an effective spray while reducing overall water consumption.
aerogenerator
A device that generates electricity from the kinetic energy produced by wind.
aggressor
1. A person or nation, that attacks or starts a war, a fight, or an argument, often without being provoked.
2. Anyone who initiates hostilities; such as, an assailant who attacks another person or who engages in some form of aggressive behavior.
3. Someone whose behavior may be violent, unpredictable, reactionary, and impulsive; for example, anyone who breaks the law.
agitator (s) (noun), agitators (pl)
1. A person who tries to stir up people in support of a social or political cause: often used in an unfavorable sense.
2. An apparatus for shaking or stirring, as in a washing machine.
alleviator (s) (noun), alleviators (pl)
A person or something that diminishes or moderates an ailment or problem : The therapist was a great alleviator of Patrick's back pain.

The new tunnel under the river will be a wonderful alleviator of the traffic going across the river on the bridge.

ambulator (s) (noun), ambulators (pl)
1. Someone who goes from place to place; a walker: Jane was a regular ambulator for several times each day.
2. An instrument for measuring distances: The surveyor was using an ambulator consisting of a wheel to roll along over the ground with a dial plate to measure the distance traveled from one point to another one.
amputator (s) (noun), amputators (pl)
A person who removes or cuts off a part of or all of the limb of the body: An amputator is a physician who has specialized in surgery: Joseph Lister was a famous English amputator who used antiseptics for the first time when operating on patients.
animator, animater (AN uh may" tuhr) (s) (noun), animators, animaters (pl)
1. Someone who makes movies that use motion, or who provides technical or artistic skills that are needed to produce movements: Mr. Long was an animator who created lively cartoons for children which could be seen on TV.
2. Someone or something that makes things lively, exciting, or interesting: Ted seemed to be an animator who was full of energy when he talked about his hobby and it sounded so thrilling and inspiring to be a mountain climber like he was.