Liquidity vs Peg/De-Pegging

The ease with which an asset can be bought or sold at its quoted price without significantly moving that price; Bitcoin and Ethereum have very high liquidity, while smaller altcoins can move significantly on modest trade sizes.

A peg is a mechanism that maintains a cryptocurrency's price at a fixed target value, typically one US dollar. De-pegging occurs when market forces or design failures cause the price to deviate significantly from that target.