Top definition. Musk. Though technically the name for the secretion of the male musk deer, musk is most often used as the name for the scent of arousal in both men and women, as actual musk is used in perfumes and colognes. Generally causes arousal for both genders, as it is a secondary sex characteristic.
These photoreceptors are called the rods and cones. Rods are called rods because under the microscope, they are shaped like, of all things, a rod. Finally, those pesky scientists named a structure for what it actually looks like as opposed to someone's unpronounceable last name!
The human eye contains two kinds of photoreceptor cells; rods and cones. Roughly 125 million of them are intermingled nonuniformly over the retina.(Hecht) The ensemble of rods(each about 0.002 mm in diameter) forms an exceedingly sensitive detector, performing in light too dim for the cones to respond to.