mar∙ket ti∙ming (verb)

1. The act of trying to time, or predict, which asset class will perform the best in the near term and focusing a portfolio in said asset class.
2. To invest in a specific asset class based on a short-term prediction.
3. To forego diversification by buying one asset class and selling another based on speculation.
4. A risky and difficult way of trying to achieve superior returns.

The above term is taken from The Steadyhand Dictionary, which is designed to help you sift through and make sense of the investment industry's dialect. Think of it as the little black book of investing.