D defs.my
Entry 2 senses Webster, 1913

Proto-

· Pro·to- · IPA /pɹoʊ.toʊ/
01 A combining form prefix signifying first, primary, primordial; as, protomartyr, the first martyr; protomorphic, primitive in form; protopla…
  1. 1.
    A combining form prefix signifying first, primary, primordial; as, protomartyr, the first martyr; protomorphic, primitive in form; protoplast, a primordial organism; prototype, protozoan.
  2. 2.
    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.(Chem.)