A glyceryl ester of oleic acid; specifically glyceryl trioleate, C₃ H₅ (C₁₈ H₃₃ O₂)₃, a colourless oily liquid which is a very common natural fat (also called triolein). Also (more widely): any liquid fat (consisting chiefly of such esters) separated from a solid or semi-solid fat; (formerly, also) †a glyceride of a fatty acid other than oleic acid (obsolete).