(1):

(n.) That which remains after a part is taken, separated, removed, or designated; remnant; remainder.

(2):

(n.) That part of a testeator's estate wwhich is not disposed of in his will by particular and special legacies and devises, and which remains after payment of debts and legacies.

(3):

(n.) Any positive or negative number that differs from a given number by a multiple of a given modulus; thus, if 7 is the modulus, and 9 the given number, the numbers -5, 2, 16, 23, etc., are residues.

(4):

(n.) That which remains of a molecule after the removal of a portion of its constituents; hence, an atom or group regarded as a portion of a molecule; - used as nearly equivalent to radical, but in a more general sense.