∙ Containing only numbers, letters, and arithmetic operators. mathematics, of an expression, equation, or function
∙ Which is a root of some polynomial whose coefficients are rational. mathematics, number theory, said of a number
∙ Describing squares by file (referred to in intrinsic order rather than by the piece starting on that file) and rank, both with reference to a fixed point rather than a player-dependent perspective. chess, of notation