noun

• One who, or that which, shifts or changes.
• (linguistics) A word whose meaning changes depending on the situation, as by deixis.
• (dated) Someone who plays tricks; a trickster.
• (nautical) An assistant to the ship's cook in washing, soaking, and shifting the salt provisions.
• (engineering) An arrangement for shifting a belt sidewise from one pulley to another.
• (engineering, textiles) A wire for changing a loop from one needle to another, as in narrowing, etc.
• (cycling) A component used by the rider to control the gearing mechanisms and select the desired gear ratio, usually connected to the derailleur by a mechanical actuation cable.
• A spanner with an adjustable jaw size.
• (mining, historical) A person employed to repair the horseways and other passages, and keep them unobstructed.
• (US, Pennsylvania) A switcher or shunter: a railroad locomotive used for shunting.
• (mythology, science fiction, fantasy) A shape-shifter, or a person or other being capable of changing their physical form.
• (erotica) A genre of erotica focusing on lycanthropes or other shapeshifters, such as werewolves.
• A shiftworker.
• (spirituality) Short for reality shifter. [(spirituality) A person who changes the reality their consciousness resides in through meditation or other means.]