It's a place name, but was also a plant name, though surely it wasn't a sweet herb.

The Fiddler's Companion says:
A pipe tune (written within the range of nine notes, with double tonic tonality) and the name of an Aberdeenshire, Scotland, estate. 'Moneymusk' is the English for the Gaelic 'Muine Muisc' meaning a noxious weed or bush. It was composed by Daniel (sometimes Donald) Dow (1732-1783) in 1776 and first appeared in his Thirty Seven New Reels, c. 1780, as "Sir Archibald Grant of Monymusk's Strathspey." Linscott (1939) says it was called "The Countess of Airly" in the early 18th century, and came from the village of Monymusk, in Aberdeenshire, Scotland." Bayard (1981) states that if Dow did "compose" the tune then he certainly had access to earlier models for it, for both "The Ruffian's Rant" and "Roy's Wife of Aldivalloch" are cognate. Alburger (1983) also identifies Daniel Dow (1732-83) as the composer of "Sir Archibald Grant of Monemusk's Reel," but says when the Gows published it in their 1799 Repository, Part First, they altered it rhythmically (by adding more 'Scots snaps' and smoothing out some dotted patterns for variety) and shortened the name to "Monymusk, A Strathspey." Dow was born in Kirkmichael, Perthshire, and became a music teacher in Edinburgh where he taught, among other instruments, the guitar. His compositions were well received in his lifetime and survive today. When he died at the age of 51 in the winter of 1783 he was buried in the Canongate Churchyard; a concert to benefit his widow and children was given shortly after his death in St. Mary's Hall, Niddry's Wynd, where he had often given his own concerts over the years.

And as a place name, click here, click here, click here, click here, or for its map and brief timeline.
To see Grant of Monymusk Clan Tartan, click here.
On the tune "Sir Archiblad Grant of Monymusk", click here too.
Didn't I give too many unnecessary click heres in this message. I hope not.