A full-page spread in the real-estate section of our local paper features one of those impossibly expensive condo buildings, this one with "signature floor-through views." I haven't any idea what a floor-through view is (tho I'm rather glad the folks upstairs don't have one). Then there's this word signature. When did it become an adjective? My M-W defines it as a noun only. I've noticed it elsewhere and the meaning is fairly clear--similar to shtick, maybe, like a comedian's signature laugh--but how can looking out the window--or through the floor--be a signature anything?