Though Latin rōs, meaning dew or light rain, has formed a number of English words, almost all of them have become either obsolete or so rare that you will seek them in vain in dictionaries.
Roscid, for example, means “dewy”:
The incense of thy stuffing fills the air,
And holds the senses in its fragrant snare;
Rich ichor from thy roscid body flows,
That e’en would tempt one in dyspepsia’s throes.
From The Chant Royal of the Turkey, in the New York Times, 22 Nov. 1903.
Another word, rorid, also means dewy, deriving from rōr-, the inflected form of rōs. So does rore (with its adjective roral). Rore is even rarer than the others, now known solely because Shakespeare used it in Timon of Athens (“My words neither aspersed or inspersed with the flore or rore of eloquence.”) Others from the same source include roriferous, bringing or bearing dew, and rorigenous, produced by dew. This last word seems to have appeared nowhere else but Nathan Bailey’s Dictionarium Britannicum of 1730. The final exhibit in this dusty museum case of unloved lexicography is irrorate, to bedew or sprinkle with dew.
Another descendant of rōs that’s still in use is rosolio, a sweet cordial of Italy which is sold commercially under brand names such as Cinzano and Martini. That name is an alteration of rōs sōlis, the dew of the sun, not as a highfalutin romantic name but because in its early days one ingredient was the juice of the sundew plant. Later it became rosa solis, rose of the sun, because rose petals were substituted for sundew.
Confusion between rōs and rosa has been endemic: rosa solis was also at one time the name of some species of sundew. And, though few know it, the plant called rosemary derives its name not from the rose but from the dew; its Latin name was rōs marinus, sea dew, because its natural habitat is sea cliffs.