If you check the TNT Express website it explains it all. TNT stands for Thomas Nationwide Transport although the best answer I was ever told when asking the question is "Tomorrow not Today"
TNT stand for ""Thomas Nationwide Transport""
Television. The entire thing is Turner Network Television
TriNitroToluene
Trinitrotoluene
Tri-nitro toluene. Toluene is a benzene ring with a methyl group attached. The nitration of this to TNT occurs at the 2,4,6 positions.