Who is a casual gamer?

Me

Someone who plays only mobile games. Or simple online games like Farmwill and etc.

Imo ''hardcore gamers'' are bunch of people trying to show they are better then others becouse (insert anything connected with gaming here). If someone wants to play any relaxing title, he/she is a gamer as well. Of course gaming industry have non shaved 30 years old guys living in mum basement grinding Super Meat Boy with carwheel too. Well, they are special.

Plays games seldom and only for relaxation; not interested in the gaming world in itself, doesn't really follow news apart from the really advertised games.
The other widely used definition is that the people who only play casual level games, mostly the types associated with Big Fish Games (match-3, marble shooter, hidden object game, solitaire, all the few-dollar mobile games, that kind of stuff).
Alternative definition: only plays Call of Duty and thinks that makes him hardcore.

i'm casual :3

i play just for fun, not competitive, don't care much about events like dota championships, don't watch streams, also like phone games.

View attached image.

What If I play shit ton of games, but no multi?

I just play games
That's enough

People who play games on easy xD
And then complain that something is too hard (on easy).

These are people who actualy have life and don't spend 6h a working day and 12h a day during weekend to max their gaming skills.

Hardcore gamers hate them, because there is more casual than hardcore gamers and developers make new AAA games easier and game mechanics more simple to fit their main targets needs.

Good question and very hard to answer. I remember my WoW days and was in a "casual" guild, that is what they called it. This consisted of 3 nights a week raiding for 4 hours each, and you had better be prepared for the raid, such as food and buffs. This didn't include the 10 mans and alt runs we usually did as well, though they weren't required. This was definitely casual compared to some of the top tier guilds that ran 6+ hours most nights and long hours on the weekends. We were generally more relaxed and I think that marks the difference between casual and hardcore, the attitude towards gaming. I believe hardcore is more into the serious gaming, trying to be one of the best.

It's one of these "why does it matter" question. Things which are hard to define typically aren't worth defining except when there's specific research involved, and even then the names don't matter.

A casual gamer who does not have a gaming platform except for a mobile device or someone who rarely uses a PC and/or console if owning one.

Hmm, few years ago I would've answered it differently, but as time passes, gaming in general is changing and evolving, in my current opinion casual gamers - those who are playing only online games (dota, cs, hearthstone, etc). It's not a matter of time, because nowadays everyone playing something, even elder generation. It's a matter of consuming something new, "casual" in this definition is doing something, that you used to, something that you've been doing for over long time already and probably gonna keep doing without changing something dramatically.