\Re*sid"u*al\ (r?-z?d"?-al), a. [See {Residue}.]
Pertaining to a residue; remaining after a part is taken.
{Residual air} (Physiol.), that portion of air contained in
   the lungs which can not be expelled even by the most
   violent expiratory effort. It amounts to from 75 to 100
   cubic inches. Cf. {Supplemental air}, under
   {Supplemental}.
{Residual error}. (Mensuration) See {Error}, 6
(b) .
{Residual figure} (Geom.), the figure which remains after a
   less figure has been taken from a greater one.
{Residual magnetism} (Physics), remanent magnetism. See under
   {Remanent}.
{Residual product}, a by product, as cotton waste from a
   cotton mill, coke and coal tar from gas works, etc.
{Residual quantity} (Alg.), a binomial quantity the two parts
   of which are connected by the negative sign, as a-b.
{Residual root} (Alg.), the root of a residual quantity, as
   [root](a-b).

\Re*sid"u*al\, n. (Math.)
(a) The difference of the results obtained by observation,
    and by computation from a formula.
(b) The difference between the mean of several observations
    and any one of them.