In physics and engineering, the time constant, usually denoted by the Greek letter ' (tau), is the parameter characterizing the response to a step input of a first-order, linear time-invariant (LTI) system.

In metrology, measurement uncertainty is a non-negative parameter characterizing the dispersion of the values attributed to a measured quantity.

According to S. Srinivasan, "The parameter characterizing the frequency dependence of the operational amplifier gain is the finite gain-bandwidth product (GB)."

Gain-bandwidth product According to S. Srinivasan "t he parameter characterizing the frequency dependence of the operational amplifier gain is the finite gain...

This is represented by a flux density B. This value of remanence is one of the most important parameters characterizing permanent magnets; it measures the strongest magnetic field they can produce.

In this equation, x is a parameter characterizing the chain length (e.g. number average molecular weight, degree of polymerization), and a is an empirically-determined constant.

One dimensionless parameter characterizing a plasma is the ratio of ion to electron mass.

The macroscopic parameter characterizing wetting of a solid (or liquid) surface with a liquid is the contact angle.

The London penetration depth is one of the most important parameters characterizing a superconductor because its inverse square provides a measure of the density n of Cooper pairs.

The "macroscopic" set of Maxwell's equations defines two new auxiliary fields that describe large-scale behavior without having to consider these atomic scale details, but it requires the use of parameters characterizing the electromagnetic properties of the relevant materials.