This word has an unmaskable manly, musty smell to it. It has the urging /mʌ/ like the sound a man may make when hefting some heavy thing, and the abrupt rustling stop of the /sk/; it rhymes with husk, rusk, tusk, and has a rough, brusque thrust to it, that musky scent perhaps mingled with labdanum… It starts with the m like muscles or a moustache (or mom, of course, but any manly man loves his mom) and ends with that hard, kicking k. The word is soaked in testosterone, or something like it (though it probably appears more often in romance novels than anywhere else).
And look what terms it shows up in. There are many compounds, certainly, that involve musk; the OED gives a long list, including musk apple, musk beaver, musk bladder, musk buffalo, but also musk carnation, musk cherry, musk geranium, musk hyacinth, musk orchid, musk-perfumed… well, no one talks about those, really – although, as we shall see, musk orchid is quite apposite.
But musk also shows up as a pseudomorpheme in assorted other manly words: imagine going out hunting for muskrat and musk ox and even muskwa (black bear) out on the muskeg with a musket and fly fishing for muskellunge like a musketeer… Hm, well, mustering that much muscular manliness may require a few mugs of muscatel or perhaps the influence of Amanita muscaria, the toadstool also known as fly agaric.
Not that flies seem all that manly. Except for fly fishing. But, then, Latin musca “fly” served as the basis for muschetta “sparrowhawk”, which came also to refer to an arrow from a crossbow, and then, it seems, from that it referred to a crossbow and (by this time having passed through the mutations of time and language transfer) then to a gun, specifically a musket. So when firing a musket you let fly from a little fly, so to speak.
This is not the origin of musk, however. Musk, I should first say, is specifically originally a greasy, odorous substance secreted by the male musk deer from a gland that hangs like a sack under its abdomen. The word comes all the way from Persian mušk and is related to or possibly even comes from Sanskrit muṣka, which means “scrotum, testicle” (the Greek word for which is the source of our word orchid, so, as I said, musk orchid is apposite – or perhaps redundant; nuts).
So you have flies, and you have what lies behind many a fly. And you have a word that sounds like heavy breath and presents a manly scent that will probably lead to the ripping of bodices…