единица физической величины(A unit of measurement is a definite magnitude of a physical quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same physical quantity. Any other value of the physical quantity can be expressed as a simple multiple of the unit of measurement. WK Alexander Demidov)
единица величины(any division of quantity accepted as a standard of measurement or exchange; a unit of measure Synonyms: unit of measure, unit. WT Alexander Demidov)