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.
but yo-yo it's also a toy (I think in English it's called the same) so, someone that is a yo-yo can mean that it is a person that can be easily manipulated like a yo-yo or a person that changes humor or personality or ideas, very frequently. Also can be referd as a person, that comes and goes, easily (like in and out of relationships)