A kludge used to make the best software from *nix and make it work in insecure, unstable environments (windows), using a method proven to create instability (DLLs).
Cygwin can be used to instantly remove all stability from any formerly secure/stable *nix program.
by packetpusher July 24, 2009
1 more definition
A set of Unix utilities ported to Windows.
Windows XP with cygwin is just as good as any Linux distro.
by w00tw00t April 05, 2003