A Thinny is a tear in the fabric of reality, which can lead to other times, parallel worlds or universes.
Wikipedia: Glossary_of_The_Dark_Tower

A thinny is a "weak spot" in reality, where the fabric of reality has been worn thin. They are described as looking like large blobs of mercury and emit a warbling sound similar to a musical saw. This sound can set a person's teeth on edge and/or hypnotize the victim.

Besides the insanity-inducing buzzing and warbling sound, the thinny plays on a person's thoughts; telling them what they want to hear and promising a fine outcome. Death is more likely. Transportation into other universes is possible by simply walking into a thinny, but this is a rare outcome.

In Wizard and Glass the main characters end up passing from All-World into Topeka, Kansas in the world of The Stand by riding Blaine the Mono through a thinny that is breaking between the two worlds. In flashbacks presented in the same novel, Roland encountered a thinny earlier in life that entered into a world filled with monsters that almost "devour" an entire army.
by Xzal May 31, 2010
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A skinny person who has a nice body. Has all the nice features as thicc girl do, but is skinny.
You saw the girl that just passed by she was thinny and cute asf.

I need a thinny girl
by Delightfol February 28, 2018
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It is a mixture between thin and skinny. A female with no breast, butt or curves. Unattractive probably anorexic. Is the opposite of thick when referring to a female.
"That girl is thinny she's got nothing on Sara" "Yeah man, Sara is thick."
by Alism95 March 31, 2017
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liquid human waste (urination) - aka pee

- opposite of thickie (shit)
"Where's the bathroom? I need to have a thinnie before I explode!"
by Holly December 05, 2007
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Pertaining to an extremely or excessively thin penis.
Megan told me her friend Dan has a thinny.
by redheadedkillla December 21, 2009
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Extremely skinny and thin at the same time
"Damn, she's thinny!"
by TrickleMeDown May 20, 2003
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Thin + skinny = thinny
"Look, that model isn't really that thinny."
by babybob22 March 29, 2015
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