proto

Definitions:

In chem., a prefix in many scientific compounds, denoting the first or smallest degree of a substance which combines with a base, as protoxide, the first or smallest proportion of oxygen; the first or earliest, as protogine; the earliest or lowest, as protozoa.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (adjective) (adj.) (adjective)
See prot.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (adjective) (adj.) (adjective)

Usage examples:

Originally a strong and able defender of the Romish doctrines, he was chosen to argue with Patrick Hamilton, the proto martyr of the Reformation in Scotland, with the object of inducing him to recant.
- A Short Biographical Dictionary of English Literature by John W. Cousin
The diverse proto historic populations, Gauls, Franks, Burgundians, and Merovingians, considered together, present a stature slightly superior to that of the French of the present day, but not so much so as the accounts of the historians would have led us to believe.
- A Philological Essay Concerning the Pygmies of the Ancients by Edward Tyson
Mr. Hunt, of the Museum of Practical Geology, instituted a series of experiments to illustrate the production of this substance, and found that decomposing vegetable matter, such as would be distributed through all coal strata, prevented the further oxidation of the proto salts of iron, and converted the peroxide into protoxide by taking a portion of its oxygen to form carbonic acid.
- The Student's Elements of Geology by Sir Charles Lyell