What is "proto-"

Proto- \Pro"to-\ [Gr. prw^tos first, a superl. fr. pro` before. See Pro-.]

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.)

   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.

before vowels prot-, word-forming element meaning "first, source, parent, preceding, earliest form, original, basic," from Greek proto-, comb. form of protos "first," from PIE *pre-, from root *per- (1) "forward, through" (see per).

pre. 1 first 2 (context linguistics genetics English) most recent common ancestor (often hypthetical) of