Literally - Too long ; Didn't read
A phrase typed in response to a blog, forum post, or other form of online media to express either that the submission of another user was either needlessly long or wordy or that the reader has a complete lack of interest in the subject matter.
Contrary to the belief held by those who experience mild to moderate butthurt due to having made submissions that either nobody cared about enough to read or were much longer than necessary for the sole purpose of condescension or self-exaltation, replying to media with "tl;dr" does not necessarily indicate substandard intelligence or an attention deficit.
This definition is a good example of a post in which replying "tl;dr" to would be appropriate.
H.Horse: "Too Long; Didn't Read" - a shining example of the sweeping Attention Deficit Disorder pandemic that seems to have embraced our society. Usually said by people who a) have never read a book, b) have no logical retort, c) want an easy laugh, or any combination of the three. Not to be confused with "TMS;DU", meaning "Too Many Syllables; Don't Understand", which is likely how some of you reading this feel about this definition.
H.Horse: I find it hilarious that any definition of TL;DR condeming those who use it as uneducated morons, are the ones receiving more thumbs down - just like this one probably will - even though they are the most accurate. That just further proves that people - especially kids - have a consistantly dwindling attention span, most likely indirectly proportional to the amount of media and entertainment devices we feel the need to constantly plug ourselves into.
Joe: No, I'm not a moron. I'm just indicating that you're pompous and arrogant and nobody cares about your novel. Also, you spelled "condemning" and "consistently" wrong.