1920, coined by Eng. physicist Ernest Rutherford (1871-1937)
from Gk. proton, neut. of protos "first,"
supposedly because hydrogen was hypothesized as a constituent of all the elements.
The word was used earlier in embryology (1893) at a transl. of Ger. anlage ("fundamental thing")
based on Aristotle's phrase he prote ousia to proton.