Physics, Chemistry. 1  a wave function describing the state of a single electron in an atom (atomic orbital) or in a molecule (molecular orbital) 2  the electron in that state.
DEFINITION of 'Yo-Yo'. Slang for a very volatile market. A yo-yo market will have no distinguishing features of either an up or down market, taking on characterstics of both. Security prices in a yo-yo market will swing very high to low over a given period of time, making it difficult for buy and hold investors to profit. Next Up.
Ball-Bearing and Transaxle Yo-Yos. Transaxle yo-yos are designed to spin for an incredibly long time. With a regular yo-yo, the string loops around the axle. With a transaxle yo-yo, a special, extremely low-resistance plastic ring touches the axle. The string wraps around the outside of the ring, but never touches the axle. This allows for extremely long spins and it also gives the string an extremely long life.