proto-

a combining form meaning “first,” “foremost,” “earliest form of,” used in the formation of compound words (protomartyr; protolithic; protoplasm), specialized in chemical terminology to denote the first of a series of compounds, or the one containing the minimum amount of an element.

Also, especially before a vowel, prot-.

Origin

< Greek, combining form representing prôtos first, superlative formed from pró; see pro-²

British Dictionary definitions for proto-

proto-

combining form

indicating the first in time, order, or rank: protomartyr

primitive, ancestral, or original: prototype

indicating the reconstructed earliest stage of a language: Proto-Germanic

indicating the first in a series of chemical compounds: protoxide

indicating the parent of a chemical compound or an element: protactinium

Word Origin

from Greek prōtos first, from pro before; see pro-²

Word Origin and History for proto-

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).

proto- in Medicine

proto- or prot-
pref.

First in time: prototype.
First formed; primitive; original: protoplast.
Having the least amount of a specified element or radical: protoporphyrin.