Liquidity

How easily something can be bought or sold quickly without moving its price much.

A share with high liquidity has many buyers and sellers close to the last price, a narrow spread, and can absorb a normal-sized order without a jump. A share with low liquidity has few, and a single large order can move its price a long way.

The same word is used for cash: money in a current account is more liquid than money tied up in a house.