prot-

combining form or proto-

Etymology: Middle English protho-, from Middle French, from Late Latin proto-, from Late Greek prōt-, prōto-, from Greek, from prōtos; akin to Greek pro before, ahead — more at for

1.

a. : first in time

protohistoric

protonymph

b. : first in status : chief in rank or importance : principal

protocerebrum

protocone

c. : beginning : tending toward : giving rise to

protofascism

protoplanet

2. chemistry

a. : first or lowest of a series : member of a series having or supposed to have the smallest relative amount of the element or radical indicated in the name to which it is prefixed

protoxide

protochloride

b. : substance held to be the parent of the substance to the name of which it is prefixed

protoactinium

c. : first or primary product of decomposition

protoproteose

3. biology

a. : archetypal

protomorph

protonephros

b. : first formed : primary

protoderm

protoxylem

4. usually capitalized : belonging to or constituting the recorded or assumed language that is ancestral to a language or to a group of related languages or dialects — usually spelled proto- and joined to a capitalized second element with a hyphen

Proto-Arabic

Proto-Indo-European

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var. of proto- before a vowel: protamine.

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prot-,

combining form. the form of proto- (Cf. ↑proto-) before vowels, as in protamine.

Prot.,

Protestant.

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comb. form variant spelling of proto- before a vowel (as in protamine)

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prot-

the form of proto- used before a vowel.