bot

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

• noun A software program that imitates the behavior of a human, as in participating in chatroom or IRC discussions.
• noun A software program, such as a spider, that performs automated tasks on the Internet.
• noun The parasitic larva of a botfly.
• noun A disease of mammals, especially cattle and horses, caused by infestation of the stomach or intestines with botfly larvae.

from The Century Dictionary.

• noun The Anglo-Saxon form (bōt) of boot, a fine, etc.: only in historical use.
• noun A name given to the larva or maggot of several species of gadfly when found in the intestines of horses, under the hides of oxen, in the nostrils of sheep, etc.
• noun An obsolete preterit of bite.
• noun A dialectal form of bat in various senses. Also spelled bott.
• noun In founding, a clay plug used to close a hole against molten iron.
• A Middle English form of but.
• noun The English Board of Trade unit of electrical supply.

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

• noun (Zoöl.) See bots.

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

• noun The larva of a bot fly, which infests the skin of various mammals, producing warbles, or the nasal passage of sheep, or the stomach of horses.
• verb UK, slang To bugger
• verb Australia, informal To ask for and be given something with the direct intention of exploiting that thing’s usefulness, almost exclusively with cigarettes.
• noun science fiction, informal A physical robot.
• noun computing A piece of software designed to complete a minor but repetitive task automatically or on command, especially when operating with the appearance of a (human) user profile or account.
• noun video games A computer controlled character in a multiplayer video game, such as a first-person shooter.

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

• noun botfly larva; typically develops inside the body of a horse or sheep or human