in physics and engineering, the density of a material.

in biology, the Rho factor protein in RNA transcription termination.

in statistics, the Spearman's rank correlation (or rho) coefficient.

in physics, the resistivity of a material.

in physics, the rho mesons, <math>\rho^+</math>, <math>\rho^0</math>, <math>\rho^-</math>.

in physics, the volume charge density.

Rhodes Diagoras International Airport, IATA code

Rho (upper case Ρ, lower case ρ) is a letter of the Greek alphabet. See Rho (letter). The lower-case letter rho (ρ) may represent:

in mathematics, the radius in a spherical coordinate system or spectral radius.

in biology, Rho GTPase, a small GTPase enzyme important in migration and stress fibre formation

Rho, a town near Milan, Italy (not to be confused with Ro, Italy)

the Rho, a Greek islet famous for its single resident, Despina Achladioti.

The Durst Rho, a series of large-format industrial inkjet printer marketed by Durst

The Right-Hand Opponent in Contract Bridge (see Contract bridge glossary)

Rho Cassiopeiae, a yellow hypergiant in the constellation Cassiopeia.