u

Definition
(noun) a base containing nitrogen that is found in RNA (but not in DNA) and derived from pyrimidine; pairs with adenine Definition
(noun) a heavy toxic silvery-white radioactive metallic element; occurs in many isotopes; used for nuclear fuels and nuclear weapons Definition
(noun) the 21st letter of the Roman alphabet Definition
(adj) (chiefly British) of or appropriate to the upper classes especially in language use