The 17th letter of the Greek alphabet, written as ρ, or a Greek letter used in science and mathematics.
From Greek 'rho' (ρ), of uncertain origin. The letter entered English through scientific and academic use, as Greek letters became standard symbols in mathematics and physics.
Rho appears in the Greek 'rho' used for electric resistance, but also in mathematics as a correlation coefficient—scientists inherited the entire Greek alphabet because in 300 BC, there simply weren't enough symbols to describe the natural world.
Complete word intelligence in one call. Free tier — 50 lookups/day.