Origin and history of prodrome

"thoroughbred Arabian camel," late 13c., from Old French dromedaire and directly from Late Latin dromedarius "kind of camel," from Latin dromas (genitive dromados), from Greek dromas kamelos "running camel," from dromos "a race course," from dramein "to run," from PIE *drem- "to run" (source also of Sanskrit dramati "runs, goes," perhaps also Old English trem "footstep").

A variety of the one-humped Arabian camel bred and trained for use as a saddle-animal, "and comparing with the heavier and slower varieties as a race-horse does with a cart-horse; it is not a different animal zoologically speaking" [Century Dictionary]. An early variant in English was drumbledairy (1560s).

1716, in pathology, "preliminary," especially of minor symptoms preceding the outbreak of a disease, from Modern Latin prodromus "a running forward" (see prodrome) + -al (1).

word-forming element meaning "forward, forth, toward the front" (as in proclaim, proceed); "beforehand, in advance" (prohibit, provide); "taking care of" (procure); "in place of, on behalf of" (proconsul, pronoun); from Latin pro (adv., prep.) "on behalf of, in place of, before, for, in exchange for, just as," which also was used as a first element in compounds and had a collateral form por-.

Also in some cases from cognate Greek pro "before, in front of, sooner," which also was used in Greek as a prefix (as in problem). Both the Latin and Greek words are from PIE *pro- (source also of Sanskrit pra- "before, forward, forth;" Gothic faura "before," Old English fore "before, for, on account of," fram "forward, from;" Old Irish roar "enough"), extended form of root *per- (1) "forward," hence "in front of, before, toward, near," etc.

The common modern sense of "in favor of, favoring" (pro-independence, pro-fluoridation, pro-Soviet, etc.) was not in classical Latin and is attested in English from early 19c.