If used in a non-political sense, "liberal" simply means "a lot."

When you eat dirt for the first time and leave your family to build a shack in the woods

A so-called "bad" thing to be before, now and probably in the future. It's been somehow turned into an attack word. What people don't realize is that no kind of progress is made without even an ounce of liberalism in your blood. Civil rights movement? Liberal from MLK Jr. Free speech/checks and balances/etc.? Liberal idea from Enlightenment thinkers. Any kind of new technology? Liberal in the sense that you want to change the existing conditions. Face it. Any kind of change, whether good or bad, is promoted by liberalism.

someone who is usually subjected to narrowminded hostility in his or her own time, but is vindicated by posterity. Many of the political figures we revere today were liberals in their own time.

Technically means those people who embrace all elements of society.

However it is more commonly used as a term for any left-winger.

People who give a shit about their fellow man.

The people who created the freedoms you live with.