Wiktionary
n. A physical property that can be measured or calculated from other physical property and expressed as the product of a numerical value and a physical unit.
Wikipedia
A physical quantity is a physical property of a phenomenon, body, or substance, that can be quantified by measurement. A physical quantity can be expressed as the combination of a magnitude expressed by a number – usually a real number – and a unit; for example, (the mass of the neutron), or (the speed of light). Physical quantities are measured as 'nu' where n is the magnitude and u is the unit. For example: A boy measured the length of a room as 3 m. Here 3 is the magnitude and m (metre) is the unit. 3 m can also be written as 300 cm. This shows that n1u1 =n2u2. Almost all matters have quantity.
Usage examples of "physical quantity".
Buzzo believed he'd found a way of tackling the calculation of any real physical quantity which made the effective contribution of all the universes of isolated points equal to zero.
Five dimensional energies which are required for teleportation are vectors-a physical quantity with both magnitude and direction.