Pitch
Relative pitch is the interval between a given sound and some other sound. Absolute pitch is the number of vibrations per second necessary to produce a given sound.
Standard pitch is the number of vibrations per second adopted as the pitch of a given sound. The standard (now almost universal) is 435. which is known as the French "diapason normal." Between 1699 and 1859 the standard rose from 404 to 455.