Noroshi
Word for today: noroshi 狼煙, "signal fire/smoke".
The kanji mean "wolf smoke", but have nothing to do with the Japanese word's etymology; they're borrowed from an old Chinese synonym. The Chinese word did really mean "wolf smoke", apparently, due to the fact that folks sending up a signal fire would mix some wolf dung in the fuel because it was said to make the smoke rise straight up.
The actual etymology of noroshi is surprisingly murky given that it isn't even attested before the 16th century. Most sources seem to agree that the noro- means "field" or "wild[erness]", closely related to the nora- in noraneko (stray cat) and noragi (fieldwork clothes). The -shi is variously attributed to shirushi (symbol), ki (air), or hi (fire).
(It's interesting to note that in Edo dialect they actually didn't distinguish hi from shi in speech—some people still speak this way in Tokyo. But I assume that this isn't directly related to the genesis of this word, since noroshi predates the Edo period itself by a century or so and in any case educated Edo folks still usually wrote the mora hi.)
Himajin:
My paper dictionary also had 烽火 for noroshi, which seems to refer to the mountaintop ROTK-style "飛ぶ火" system they had back in the ritsuryo days. Maybe the sound was borrowed after this went out of use?