See Also: Proto-(medicine)
proto-(dictionary)
proto-(dictionary)
Proto-oncogene(medicine)
Proto-oncogenes(health)
proto-oncogenes(medicine)
proto-oncogene proteins c-met(medicine)
Proto-Geometric style(encyclopedia)
proto-oncogene proteins(medicine)
proto-oncogene proteins c-raf(medicine)

proto- (iou)



proto- combining form. Before a vowel or h also prot-.
[Greek proto- combining form of protos first: see -O-.]
1. First in time, earliest, original; at an early or preceding stage of development, primitive; spec. (Linguistics) designating or pertaining to the earliest attested or hypothetically-reconstructed form of a language or language family.
2. First in rank or importance.
3. Chiefly Science. First in position, anterior.
b. Chemistry. Forming names of: (a) (esp. binary) compounds in which an element combines in the smallest proportion with another element; (b) precursors or parent compounds, structures, etc.
protobiont Biology a membrane-bound fluid droplet containing complex organic molecules, hypothesized as ancestral to living cells M20.
protoca'nonical adjective of, pertaining to, or constituting a first or primary canon (of sacred books) E17.
proto'cercal adjective [Greek kerkos tail] Ichthyology designating or possessing a tail of primitive form, symmetrical and continuous with the dorsal and ventral fins L19.
proto'chlorophyll noun (Biochemistry) a naturally occurring photoactive precursor of chlorophyll L19.
proto'chordate adjective & noun (Zoology) (of, pertaining to, or designating) an animal belonging or related to the chordates but lacking a skull and vertebrae (i.e. other than a vertebrate), i.e. a cephalochordate, a urochordate, or a hemichordate: L19.
protoconch noun the embryonic shell in molluscs, freq. retained at the tip of the adult shell L19.
, Medicine & Zoology a vesicle formed from a hydatid cyst and capable of developing into a tapeworm scolex L20.
protostele noun (Botany) a simple type of stele, found esp. in the roots of seed plants, in which a central core of xylem is surrounded by a cylinder of phloem E20.
protostelic adjective pertaining to or of the nature of a protostele E20.
protostar noun (Astronomy) a contracting mass of gas representing a star in an early stage of formation, before nucleosynthesis has begun M20.
proto'stellar adjective (Astronomy) of, pertaining to, or of the nature of a protostar or protostars L20.
protostome noun (Zoology) a metazoan organism whose mouth develops from the primary embryonic opening or blastopore, as an annelid, a mollusc, an arthropod M20.
prototroch noun [Greek trokhos wheel] Zoology a ciliated ridge encircling the body of a trochosphere larva in front of the mouth L19.
prototy'pographer noun (a) the earliest printer; (b) a chief printer: M17.
protovirus noun (Biology) a body of genetic material, esp. RNA, which cannot reproduce but from which a virus or infective particle may arise under certain circumstances L20.
proto'xylem noun (Botany) the part of the primary xylem which is formed first, found in plant tissue which is still elongating L19.