1. A flat white square with two wires coming out of it, that, when hooked up to electricity, becomes hot on one side and cold on the other. Reversing the connections will swap the hot and cold sides. A solid-state heat pump. Found inside those iceless 12 volt coolers and on some overclocked computer chips. They are not usually used as a room air conditioner because they have a energy efficiency rating of less than 1, i.e. they generate more heat than they move. They have the advantages that there's no mechanical parts to break down, and no environmental issues with refrigerants such as the Freon used in a compressor, and they operate at 40dBa with fan instead of the 68 dBa of a commercial compressor with fan (read: much quieter)
2. A person's last name, so called because the first Peltiers used to collect pelts like fur trappers.
1. "My friend hooked up his peltier backwards, cooling his heatsink and heating his processor."
2. L. Peltier went out fur trapping with Phillipe Charmeoux back in the fairytale era.