means Describing someone of high birth or rank, or behavior marked by honor and generosity of spirit — and in chemistry, an element so unreactive it stays splendidly to itself.

from From Latin 'nobilis,' meaning 'well-known, famous, of high rank,' which traces back to the root of 'noscere,' 'to know' — the noble were literally the notable, the people everyone knew of. It reached English through Old French 'noble.' The chemistry sense ('noble gases,' 'noble metals') borrows the same aristocratic snobbery: these elements are too dignified to mingle and bond with the common rabble of the periodic table.