α  alpha 
angular acceleration,
Helium nucleus,
temperature coefficient of resistivity,
coefficient of linear expansion,
Van der Waals interaction energy

β  beta (e pronounced as long a)  electron,
coefficient of volume expansion,
volume occupied by molecules

χ  chi (ch pronounced as k, long i) 
timedependent portion of the electron wave function,
number of degrees of freedom

Δ  Delta  finite change 
ε  epsilon 
electrical permittivity,
efficiency

γ  gamma  photon,
ratio of specific heat at constant pressure to specific heat at constant volume

κ  kappa 
dielectric constant,
polytropic index

λ  lambda 
linear charge density,
wavelength

μ  mu  micro,
coefficient of friction,
magnetic moment,
magnetic permeability,
linear mass density

ν  nu (pronounced new) 
frequency,
molar volume

ω  omega (e pronounced as long a) 
angular velocity,
angular frequency

Ω  omega 
Ohms,
number of accessible states

φ  phi  an angle,
phase angle,
work function

Φ  phi 
electric flux,
magnetic flux

π  pi (long i)  number of radians in 180 degrees 
ψ  psi (long i) 
electron wave function

ρ  rho (pronounced row)  density,
volume charge density,
electrical resistivity

σ  sigma 
surface charge density,
electrical conductivity,
StefanBoltzmann constant,
standard deviation

Σ  sigma  Sum 
τ  tau 
torque,
time constant

θ  theta  an angle 