|"I'm an extant gown with a skirt of great extent"|
A big one...
Extant - (adjective)
1. in existence; still existing; not destroyed or lost
2. Archaic. standing out; protruding.
Extent - (noun)
1. the space or degree to which a thing extends; length, area, volume, or scope.
2. something extended, as a space; a particular length, area, or volume; something having extension.
These definitions come from Dictionary.com, which also has a handy audio pronunciation to listen to.
So now you know! Don't get caught using the wrong words!