definitions

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.

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Nearby words

protista, protistan, protistology, protium, proto team, proto-, proto-algonquian, proto-doric, proto-elamite, proto-form, proto-germanic
Also especially before a vowel, prot-.

Origin of proto-

< Greek, combining form representing prôtos first, superlative formed from pró; see pro-2
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for proto-

proto-

sometimes before a vowel prot-

combining form

indicating the first in time, order, or rankprotomartyr
primitive, ancestral, or originalprototype
indicating the reconstructed earliest stage of a languageProto-Germanic
indicating the first in a series of chemical compoundsprotoxide
indicating the parent of a chemical compound or an elementprotactinium

Word Origin for proto-

from Greek prōtos first, from pro before; see pro- ²
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for proto-

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).

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine 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.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.