Simple Definition:

Liberal means being open to new ideas and willing to change traditional views. The word "liberal" usually refers to a person who believes in individual freedom [people being free to do and think whatever they desire to] and equality [everyone having the same rights]. For example, a liberal might support policies that support same-sex marriage [when two people of the same gender get married] or aim to provide affordable healthcare for all [making sure everyone can go to the doctor without it being too expensive].

Very Simple Definition:

Liberal means being open to new ideas and believing that everyone should have the same rights and be treated fairly. For example, a liberal person may want everyone to have healthcare [medical care and treatment] without it being too expensive. They might also support same-sex marriage [when two people of the same gender get married].