Liquidity denotes the availability of funds for making payments and the ease with which an asset can be realised as cash. Cash itself has the highest degree of liquidity. A bank deposit is less readily available when it is held for a longer fixed term. The expression is also used in a broader monetary sense to mean money or funds that can be accessed without delay.
Source: European Central Bank (ECB) (source). This glossary entry is an independently worded adaptation of the cited information.