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.
The test A yo-yo test involves a player shuttling between two cones that are set 20 metres apart on flat ground. He starts on a beep and needs to get to the cone at the other end before the second beep goes. He then turns back and returns to the starting cone before the third beep. That is one shuttle.