a strictly medical term, used to describe a patient or person that has delved into a realm of irrational, illogical and/or crazy thought processes; Affected with madness; insane to an exceeding degree characterized by weakness or feebleness; decrepit; broken; falling to decay; shaky; unsafe; foolish

Kryptonite is a compound consisting of the element krypton, according to chemical-forming "-ite" nomenclature of chemistry.
However, krypton is a planet where Superman Clark Kent comes from and the substance kryptonite from it due to the explosion is fatal to our Superman, i.e. the translucently green rocks you would see in the TV series and which make Clark Kent dizzy and feeble and can even kill him.
Thus figuratively, it means something that makes you weak, powerless and limp, i.e. your weakness, whenever it comes to you, because it can even weaken Superman, let alone you!

The feeling of fatigue and/or lethargy succumbing to the point of disability as a result of ingesting certain chemical compounds.

1. Adj. Weak; lame; pussy; pathetic; stupid; retarded, idiot, dumb-ass comical in its sheer idiocy or feebleness. Subpar;
2. A really lame object/person or action
3. With gamers, it usually refers to the lame actions or ineffective gameplay referring to the awkwardness of their movements or lack of coordination while playing and thus getting owned.
4. Used when frustrated as well when the pony is the source of the frustration

Named for its putative inventor, mathematician David Hilbert (who some claim found the solutions for Einstein's equations before "L'il Albie" did himself), Hilbert Space is a concept which has been often applied in mathematics, quantum mechanics, and in general metaphysics (for instance, concepts like "parallel universes").

In short, a Hilbert Space is a mathematical construct such that within any plenum of n-dimensional spaces there exists an infinite number of said Hilbert Spaces (subsumed within an n+1 dimensional superset). Fancifully, science fiction writers point to the infinite plurality of 4D Hilbert Spaces that could exist within our "normal" 5D continuum, and suggest that each such Hilbert Space may really exist and that these Hilbert Spaces could be engendered by time-travel to the past. Thus, each 4D Hilbert Space in a 5D superset of "Universes" could possess a unique history, entirely different from all other universes contained within the 5D "Universe".

to have traits that are more often associated with traditional feminine behaviour, conduct, style and gender roles rather than masculine behaviour, conduct, style and roles.

Pertaining to a general state of feebleness, a lack of strength, durability or vigor.