Very small measurement used by toolmakers & engineers, or roughly .0001 or one ten thousandth of an inch. Actual size may vary between shops, but always much less than a pussy hair. About one tenth of a skosh which is equal to approximately one nudge of the dial.
Note: When specified, generally regarded as smaller than the smallest one can measure or produce, since while most people intuitively understand that a gnat's ass is pretty small, few have actually bothered a gnat to measure one.
Acronym for Graphical Network Address Translation Securtiy Tool and Information. A tool that analyzes a NAT table and displays information about current connections in a graphical format, bringing attention to possible security breaches like non-standard ports, connections to terrorist countries, etc.
Dude, I was using GNATSTI and saw that my computer was communicating with China over TCP port 6667; I think I'm part of a bot-net.