alsoazure, indigo[? bluegown under blue adj.1 , the Fr. Bibliothèque bleue, ‘a series of books of questionable character’ (F&H) or as the opposite of brown adj.2 (1); note the papier bleu which in 18C covered the pornographic or seditious material on the tray of a colporteur, an itinerant Parisian bookseller]
[early 19C+] coarse, obscene, pornographic; thus blue film, blue movie; thus, constr. with the, coarseness, obscenity.
see separate entry.
burn it blue
[early 18C] to act outrageously, poss. by speaking very coarsely.
make the air blue
(alsomake the air turn blue, turn the air blue)