any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter
in or belonging to the air or operating (for or by means of aircraft or elevated cables) in the air; "aerial particles"; "small aerial creatures such as butterflies"; "aerial warfare"; "aerial photography"; "aerial cable cars"
completely lacking nobility in character or quality or purpose; "something cowardly and ignoble in his attitude"; "I think it a less evil that some criminals should escape than that the government should play an ignoble part"- Oliver Wendell Holmes, Jr.
not of the nobility; "of ignoble (or ungentle) birth"; "untitled civilians"
lacking even the rudiments of courage; abjectly fearful; "the craven fellow turned and ran"; "a craven proposal to raise the white flag"; "this recreant knight"- Spenser