bot vs engine

bot

noun
  • A piece of software designed to perform a minor but repetitive task automatically or on command, especially when operating with the appearance of a (human) user profile or account. 

  • The larva of a botfly, which infests the skin of various mammals, producing warbles, or the nasal passage of sheep, or the stomach of horses. 

  • A physical robot. 

  • A computer-controlled character in a video game, especially a multiplayer one. 

  • A supremely unskilled player. 

verb
  • To ask for and be given something with the direct intention of exploiting the thing’s usefulness, almost exclusively with cigarettes. 

  • To bugger. 

  • To use a bot, or automated program. 

engine

noun
  • A software or hardware system responsible for a specific technical task (usually with qualifying word). 

  • A person or group of people which influence a larger group; a driving force. 

  • Anything used to effect a purpose; any device or contrivance; an agent. 

  • A self-powered vehicle, especially a locomotive, used for pulling cars along a track. 

  • A large construction used in warfare, such as a battering ram, catapult etc. 

  • The part of a car or other vehicle which provides the force for motion, now especially one powered by internal combustion. 

  • A complex mechanical device which converts energy into useful motion or physical effects. 

How often have the words bot and engine occurred in a corpus of books? (source: Google Ngram Viewer )