Presumably the "Ti" in TikZ comes from Till Tantau. If so, what does the rest of the name stand for? If not, why is the package named that way?
It's a recursive acronym and it is explained in the manual.
(German for: TikZ is not a drawing program)
I guess the first letter T stems from Till Tantau.
Just in case the question comes up, PGF stands for “portable graphics format“. From the manual as well (emphasis is mine):