The Greek letter "ν" (nu) is the 13th letter of the Greek alphabet. In the Greek numeral system, it has a value of 50. It is commonly used in various fields, including mathematics and physics, to represent specific variables or constants. In mathematics, "ν" often denotes frequency in physics, particularly in wave mechanics. It can also represent the number of degrees of freedom in statistics. Additionally, in the context of particle physics, "ν" is used to symbolize neutrinos, which are subatomic particles with very little mass.