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
proto historic
proto nymph
b. : first in status : chief in rank or importance : principal
proto cerebrum
proto cone
c. : beginning : tending toward : giving rise to
proto fascism
proto planet
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
prot oxide
proto chloride
b. : substance held to be the parent of the substance to the name of which it is prefixed
proto actinium
c. : first or primary product of decomposition
proto proteose
3. biology
a. : archetypal
proto morph
proto nephros
b. : first formed : primary
proto derm
proto xylem
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