proto- Meaning, Definition & Usage

Pro"to-
Etymology
Gr. prw^tos first, a superl. fr. before. See Pro-.
Definitions
  1. A combining form prefix signifying first, primary, primordial; as, protomartyr, the first martyr; protomorphic, primitive in form; protoplast, a primordial organism; prototype, protozoan.
  2. (Chem.) (a) Denoting the first or lowest of a series, or the one having the smallest amount of the element to the name of which it is prefixed; as protoxide, protochloride, etc. (b) Sometimes used as equivalent to mono-, as indicating that the compound has but one atom of the element to the name of which it is prefixed. Also used adjectively.

Webster 1913