-A past instance of active thought, to deliberate upon a problem or a solution.
-The action of thinking.
-The active analytic process of thinking and organizing information in order to make a decision.

The word date back from early 90's, when during a conversation between two person one needed to describe something but the word "pensive" was not suited to the sentence and thinking was too immediate.

thinkster

Something an avetard does after you ask him a basic ass question. You can ask him the most simple shit and he will not respond for like 15 mins and when you ask him again he'll be like "i was thinking" it's pretty obvious that this dude is dumb as shit and useless af.

Slang for the endless stream of thoughts that plague your mind, one after the other, especially when trying to fall asleep.

A complex process that typically involves head scratching and "Hmm" noises, and is often followed by an "aha!" in normal people, or a stupid comment in cheerleaders.

what I don't do during class

The last thing most people do before acting.
An activity that's frowned upon and made taboo by every society, culture, religion, government, cult, fad, or any other large group of people.