Equal in value, force, measure, power, effect, import, or meaning; correspondent; agreeing; tantamount: as, circumstantial evidence may be almost equivalent to full proof.In geology, contemporaneous in origin; corresponding in position in the scale of rocks: as, the equivalent strata of different countries. See II., 2.In geometry, having equal areas or equal dimensions: said of surfaces or magnitudes.In biology, having the same morphic valence; homologous in structure.n. That which is equal in value, measure, power, force, import, or meaning, to something else; something that corresponds, balances, compensates, etc.n. In geology, a stratum or series of strata in one district formed contemporaneously with a stratum or series of a different lithological character in a different region, or occupying the same relative position in the scale of rocks, and agreeing in the character of its fossils if deposited under similar circumstances: thus, the Caen building-stone of France is the equivalent of the English Bath oölite.To produce or constitute an equivalent to; answer in full proportion; equal or equalize.In geometry: Said of two polygons if they can be cut into a finite number of triangles congruent in pairs.In chem., applied to the respective quantities of different substances which are capable of replacing each other in combination with a fixed quantity of some particular substance. These mutually replaceable quantities of such substances are said to be equivalent to each other. See equiralence. 2.n. See equivalence, 2.