Proto

Webster's Dictionary

(1): 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.

(2): 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.

(3): A combining form prefix signifying first, primary, primordial; as, protomartyr, the first martyr; protomorphic, primitive in form; protoplast, a primordial organism; prototype, protozoan.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature

(first). This adjective is prefixed to the name of several officers in the Greek Church, denoting that he who holds it is the chief of his class such as prothonotary, protoppaas, protopsaltes, protosyncellus.