Liquidity

n. quality or state of being liquid; interchangeability of assets and money

Market liquidity is a business, economics or investment term that refers to an asset's ability to be easily converted through an act of buying or selling without causing a significant movement in the price and with minimum loss of value. An act of exchange of a less liquid asset with a more liquid asset is called liquidation. Liquidity also refers both to that quality of a business which enables it to meet its payment obligations, in terms of possessing sufficient liquid assets; and to such assets themselves.
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Noun
1. the state in which a substance exhibits a characteristic readiness to flow with little or no tendency to disperse and relatively high incompressibility
(synonym) liquid, liquidness
(hypernym) state of matter, state
2. the property of flowing easily
(synonym) fluidity, fluidness, liquidness, runniness
(hypernym) thinness
3. being in cash or easily convertible to cash; debt paying ability
(hypernym) exchangeability, interchangeability, interchangeableness, fungibility

(n.)
The state or quality of being liquid.
  

A market is liquid when it has a high level of trading activity, allowing buying and selling with minimum price disturbance. Also a market characterized by the ability to buy and sell with relative ease. Antithesis of illiquid.