proto-

American  

1. 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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proto- British  

combining form

1. indicating the first in time, order, or rank

   protomartyr

2. primitive, ancestral, or original

   prototype

3. indicating the reconstructed earliest stage of a language

   Proto-Germanic

4. indicating the first in a series of chemical compounds

   protoxide

5. indicating the parent of a chemical compound or an element

   protactinium

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Usage

What does proto- mean? Proto- is a combining form used like a prefix meaning “first,” "foremost,” or “earliest form of.” In terms from chemistry, it specifically denotes the first in a series of compounds or the compound containing the minimum amount of an element. It is often used in scientific and technical terms, especially in biology.Proto- comes from Greek prôtos, meaning “first.” The word proton, meaning "a positively charged elementary particle," ultimately shares this same Greek root. The Latin cognate of prôtos is prīmus “first,” which is the source of primary and prime. Check out our entries for both words to learn more.What are variants of proto-?When combined with words or word elements that begin with a vowel, proto- becomes prot-, as in protium. Want to know more? Read our Words That Use prot- article.

Etymology

Origin of proto-

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

Example Sentences

Researchers from MIT and collaborating institutions have uncovered exceptionally rare traces of "proto Earth," the ancient precursor to our planet that existed about 4.5 billion years ago.

From Science Daily

These meteorites gradually merged through repeated impacts to create the proto Earth and its neighboring planets.

From Science Daily

They reasoned that if the proto Earth were originally made from such potassium-40-deficient materials, then most of this material would have undergone chemical changes -- from the giant impact and subsequent, smaller meteorite impacts -- that ultimately resulted in the materials with more potassium-40 that we see today.

From Science Daily

While the meteorites in the team's previous work showed potassium anomalies, they aren't exactly the deficit seen in the proto Earth samples.

From Science Daily

But could the samples be rare remnants of the proto Earth?

From Science Daily