A very sensitive person. Someone who is easily hurt or offended by the statements or actions of others.

This has nothing to do with politics. Snowflakes can be liberal or conservative. Whether it is a compliment or an insult is a matter of opinion and depends on the context.

It's the sweat that accumilates under big boobs

A hypersensitive, irrational person who can't stand to have their world views challenged, or be offended in any perceived or even slightest of ways; they will have any number of emotional reactions: impuning character and/or motives, blocking on social media, shouting, interrupting, threatening, assaulting, etc. They often live in an echo chamber of their own beliefs and surround themselves exclusively with people and opinions that agree with their own. This term is most often use to describe people left-leaning people, but can be applied both left and right wing people.

An individual who is easily triggered by holiday cups at Starbucks and other things that don't bother the rest of society.

A flake that is mostly made of snow.

A flake of that white stuff that comes out of the sky in the winter.

An overly sensitive person that doesn't take criticism well.
Donald J Trump.