What does the term "saturated hydrocarbon" refer to?

The term "saturated hydrocarbon" specifically refers to a hydrocarbon that contains only single bonds. Saturated hydrocarbons are compounds where each carbon atom is bonded to as many hydrogen atoms as possible, meaning they have the maximum number of hydrogen atoms for a given carbon skeleton. This is due to the absence of double or triple bonds, which would reduce the number of hydrogen atoms that can be attached to the carbon chain.

In contrast, hydrocarbons with double bonds (which would indicate unsaturated hydrocarbons) or those with triple bonds would not be classified as saturated, as these bonds allow for fewer hydrogen atoms relative to the number of carbon atoms. Functional groups introduce other elements besides carbon and hydrogen, making those compounds fundamentally different from simple hydrocarbons. Thus, the defining characteristic of saturated hydrocarbons is that they contain only single bonds, allowing for maximum hydrogen saturation.