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 of proto-

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

Words nearby proto-

protist, protista, protistology, protium, proto team, proto-, proto-algonquian, proto-doric, proto-elamite, proto-form, proto-germanic

Example sentences from the Web for proto

British Dictionary definitions for proto

proto-

sometimes before a vowel prot-

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 for proto-

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

Medical definitions for proto

proto-

pref.

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