So, is WINE a Windows emulator or a Windows emulation ?
WINE is an open source implementation of the publicly available Win32 APIs.
Related projects:
Windows Services for Linux is an implementation of the Linux kernel APIs.
AROS is an implementation of the Amiga APIs.
Haiku is an implementation of the BEOS API's.
GNU is an implementation (and extension) of the UNIX APIs.
Android is an implementation of the Java APIs.
And so on..... No emulation involved.