Etymology is the study of the history of words, their origins, and how their form and meaning have changed over time.
Heart when people in your presence lay claim to modern liberalism by uttering a predominant meme. Jump on this opportunity to demonstrate their ignorance. However, be undeterred by the infancy of their thought processes regarding basic concepts of ideology and engage them in substantive debate?
You wish! Ask them whether it's understandable for others to act in liberal fashion. For example, those opposing a mandate to buy a product or service by virtue of being alive, who exult the incandescent light bulb, that vote Republican and happen to be Hispanic, pro-life teachers. At this point, anything that upsets an intolerant, closed minded person might be submitted.
Once they're outed as beyond dissimilar to "liberal", it may be high time to find an exit. But don't forget to remind them that, "liberal" is a suitable word to describe you, albeit not without simple context.