proto-

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.

An example of a term from botany that features proto– is protoderm, “a thin outer layer of the meristem in embryos and growing points of roots and stems, which gives rise to the epidermis.”

The proto– part of the word means “earliest form of,” as we already know. The –derm part of the word may also look familiar; it means “dermis,” which is the dense inner layer of skin. Protoderm literally translates to “earliest form of skin.”

What are some words that use the combining form proto-?

• protocol (using the equivalent form of proto- in Greek)
• protogenic
• protohuman
• protoplasm (using the equivalent form of proto- in Greek)
• protostome
• prototype (using the equivalent form of proto- in Greek)

What are some other forms that proto– may be commonly confused with?

• pro-
• proct-
• procto-
• proteo-
• protero-

The form -type literally means, well, “type.” With this in mind, what does prototype literally mean?