Thumbnail 

The cover photo for a YouTube video. Usually to get your attention or show what the video is about.

Put boobs in the thumbnail to get more views dude!

Thumbnail by TheRedBeanie__ July 20, 2016

thumbnail 

the little pictures that make looking at porn so much easier and simplier

i looked at all the thumbnails of the dirty bitch

thumbnail by themainevent November 17, 2003

Thumbnail 

1 - The nail of the thumb
2 - Something that is small or brief; concise
3 - A printing; small and rough

1 - Look at Joe's bleeding thumbnail!
2 - Jane quickly wrote a thumbnail summary of the chapter she had read.
3 - Bob drew a thumbnail sketch of his idea before he started his actual picture.

Thumbnail by 7sdrawkcab May 3, 2009

thumbnail 

Someone who looks really hot seen from a distance who when viewed in close proximity turns out to be butt ugly.

That hot guy walking up the beach turned out to be a fat grandpa, what a thumbnail!

thumbnail by Phil A Buster January 13, 2011

Thumbnail 

Lana Rhoades

Bye Mike! Bye Thumbnail!

Thumbnail by lightetet May 27, 2021

Thumbnail Syndrome 

The phenomenon in which someone seems far more attractive in the thumbnail version of a profile picture than they truly are.

I thought the girl who sent me a friend request was hot, but it turned out to be a case of Thumbnail Syndrome.

Thumbnail Syndrome by Ken_II July 27, 2009

Thumbnail Hot

When someone looks like they might be attractive in their Facebook or Twitter thumbnail until you click on it and find out that they're really not.

"Yeah, at first I thought he was really hot but turns out he was only thumbnail hot."

Thumbnail Hot by jeatags March 31, 2009