Avoid the misspelling nickle. A metallic bioelement, atomic no. 28, atomic wt. 58.6934, closely resembling cobalt and often associated with it. Protects ribosome structure against heat denaturation. A deficiency of nickel causes changes in the ultrastructure of the liver. It is a cofactor in various henzymes (e.g., urease). [abbrev. fr. Ger. kupfer-nickel, name of copper-colored ore from which nickel was first obtained; nickel, the Ger. word for a dwarfish imp]