from The American Heritage® Dictionary of the English Language, 4th Edition
- First in time; earliest: protolithic.
- First formed; primitive; original: protohuman.
- Being a form of a language that is the ancestor of a language or group of related languages: Proto-Germanic.
- Having the least amount of a specified element or radical: protoporphyrin.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- Used to form the name of the hypothetical ancestor of a family of languages.
from the GNU version of the Collaborative International Dictionary of English
- A combining form prefix signifying first, primary, primordial
- Denoting the first or lowest of a series, or the one having the smallest amount of the element to the name of which it is prefixed; as protoxide, protochloride, etc.
- Sometimes used as equivalent to mono-, as indicating that the compound has but one atom of the element to the name of which it is prefixed. Also used adjectively.
from The Century Dictionary and Cyclopedia
- n. An element in compound words of Greek origin, meaning ‘first,’ and denoting precedence in time, rank, or degree.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. indicating the first or earliest or original
Greek prōto-, from prōtos; see per1 in Indo-European roots.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Ancient Greek πρωτο- (proto-), combination form of πρῶτος (protos, "first"), superlative of πρό (pro, "before"). (Wiktionary)