\Pro"te*id\, n.
{Defensive proteid} (Physiol. Chem.), one of a class of
   proteid substances, present in some animal tissues and
   fluids, that make the body immune to certain infectious
   diseases by destroying or rendering inactive the toxic
   products of bacterial growth.

\Pro"te*id\, n. [Gr. prw^tos first.] (Physiol. Chem.)
One of a class of amorphous nitrogenous principles,
containing, as a rule, a small amount of sulphur; an
albuminoid, as blood fibrin, casein of milk, etc. Proteids
are present in nearly all animal fluids and make up the
greater part of animal tissues and organs. They are also
important constituents of vegetable tissues. See 2d Note
under {Food}. -- {Pro"te*id}, a.