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

1. Technically, someone who falls to the left in a political system, who believes in government programs (healthcare is a good example, as is welfare) and a larger scope of government, also favors monitoring of business and protection of constitutional rights. Someone who believes that the federal government should have more importance than state government,

2. Somehow, it has turned into an insult, like the word conservative. Usually used as such by people who have never taken a political science class and don't know what the word means. Often used to describe "liberal media" despite the fact that most media outlets are owned by conservative corporations like ClearChannel, and the prevalence of conservative talk shows.

A liberal, in the American sense, is one who falls to the left in the political spectrum; In other parts of the world, however, liberalism is the belief in laissez-faire capitalism and free-market systems - hence the recently coined term, neoliberalism.

Although I do not like to generalize, for the purposes of a (somewhat) concise dictionary definition, here is the very basic liberal (American sense) ideology:

Politics:
The federal government exists to protect and serve the people, and therefore, should be given sufficient power to fulfill its role successfully. Ways in which this can be accomplished include giving the federal government more power than local governments and having the government provide programs designed to protect the interests of the people (these include welfare, Medicare, and social security). Overall, these programs have helped extensively in aiding the poor and unfortunate, as well as the elderly and middle class.
To make sure that the interests of the people are served, it was liberals (or so they were considered in their time) that devised the idea of a direct democracy, a republic, and modern democracy. This way, it is ensured that the federal government represents the interests of the people, and the extensive power that it is given is not used to further unpopular goals. Liberals do not concentrate on military power (though that is not to say they ignore it), but rather focus on funding towards education, improving wages, protecting the...

Essentially, a gay hippie.

Adjective - Falling to the left on the political spectrum of the average person, being in favour of more government control of economic actions (such as making minimum wage laws), but less governmental control of personal actions (such as allowing protesting)
noun - Any person who is liberal, as desribed above

noun: A person who, because of a brilliantly ineffectual two-party system, has been made out as the "enemy of democracy" in the minds of those currently in power. Every vicious, hateful post against these people (and against conservatives) helps take our minds off of the real ills of society so that we may feel like we're doing good by hating SOMETHING.

Liberal is a person with liberal views. However, an EXTREME liberal is the WORST type of person. To start with they brainwash people. Then they convince you that their pre made views they hand to you are open minded. They tell you to hate Republicans and everyone who thinks differently than you. They are the first to throw around the word racist. Most extreme liberal abuse minorities. They look for a group typically blacks or hispanics, convince them they are nothing and need the liberals to survive, then exploit them for political power. Extreme liberals are usually igorant but claim everyone else is. They pretend to be looking out for the people but are only looking out for themselves. Some day people will realize this is the truth.