Definition of "rho"

rho

/ɹəʊ/

noun
plural rhos
1. The seventeenth letter of the Modern Greek and Classical alphabets and the nineteenth letter of Old and Ancient.
  Quotations
  Greek was an exercise in making the familiar strange. Its alphabet mapped onto the Roman alphabet, but only partly so, and often letters did not sound how they looked – a rho (Ρ) was not a P, and an eta (Η) was not an H.
  2022, R. F. Kuang, Babel, HarperVoyager, page 25
2. (finance) The sensitivity of the option value to the risk-free interest rate.