Proto-Norse
— Noun
– English
～ the Germanic language of Scandinavia up until about 700
protoactinium
— Noun
– English
～ a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
protoanthropology
— Noun
– English
～ the study humans prior to the invention of writing
protoarchaeology
— Noun
– English
～ the study of prehistoric human artifacts and human fossils
protoarcheology
— Noun
– English
～ the study of prehistoric human artifacts and human fossils
protoavis
— Noun
– English
～ most primitive avian type known; extinct bird of the Triassic having bird-like jaw and hollow limbs and breastbone with dinosaur-like tail and hind limbs
protoceratops
— Noun
– English
～ small horned dinosaur
protocol
— Noun
– English
～ (computer science) rules determining the format and transmission of data
protocol
— Noun
– English
～ code of correct conduct; "safety protocols"; "academic protocol"
protocol
— Noun
– English
～ forms of ceremony and etiquette observed by diplomats and heads of state
protoctist
— Noun
– English
～ any of the unicellular protists
protoctist family
— Noun
– English
～ any of the families of Protoctista
Protoctista
— Noun
– English
～ in most modern classifications, replacement for the Protista; includes: Protozoa; Euglenophyta; Chlorophyta; Cryptophyta; Heterokontophyta; Rhodophyta; unicellular protists and their descendant multicellular organisms: regarded as distinct from plants and animals
Pieris protodice
— Noun
– English
～ common North American form of cabbage butterfly
protoheme
— Noun
– English
～ a complex red organic pigment containing iron and other atoms to which oxygen binds
protohemin
— Noun
– English
～ a reddish-brown chloride of heme; produced from hemoglobin in laboratory tests for the presence of blood
protohippus
— Noun
– English
～ Pliocene horse approaching donkeys in size
protohistory
— Noun
– English
～ the study humans prior to the invention of writing