What Do The Words Conservative And Liberal Mean?

Conservative and liberal are two opposites and defined in the following ways.
Conservative as defined by the dictionary is  conventional, following convention. or norms.to preserve the past norms.
In politics it is often defined as the right, so in Britain we have the conservatives, and in America the republicans.
Preservative has another meaning, as a noun,  a food additive to preserve food.
Liberal on the other hand means freethinking, not given to convention, and open to change or reform.
In politics it is defined as the left, so in Britain we have the liberals and in America the democrats.
liberally is often used as an adverb, for example, he spread butter liberally on his sandwich