This is not a word you will find in a dictionary .... yet. It is a strong insult combining two words 'liberal' and 'retard'. Politically, conservative / right-wing leaning thinkers consider liberal thinkers to be too soft, relaxed, too easily offended and and allowing society too much expression. They consider this to be a bad thing, stupid or retarded - a very nasty way to describe someone you think is of low intelligence. Hence, along with being a 'snowflake' (one who is too easily offended by small things) we now have Libtard. (Liberal Retard).

I think Mirella's definition is off key; it's a term used by internet Republicans for anyone who isn't a Republican (btw this is Ben Shapiro, whose work is admired by terrorists, recently interviewed: https://www.youtube.com/watch?v=6VixqvOcK8E)

A retard who likes to talk ad lib, probably.

Ummm I got it. Thanks for your answer.

It's a recently invented, rarely used term of abuse for someone of different political views. Its function is to identify its user as a right wing extremist in US politics. It's probably better that you recognise it but never use it :)