Actually, the formal definition of macro photography is magnification greater than 1:1. Micro photography is up to 1:1.
Wikipedia says "Macro photography (or photomacrography or macrography, and sometimes macrophotography), is extreme close-up photography, usually of very small subjects, in which the size of the subject in the photograph
is greater than life size"
(their following sentences clarify that it is size on the sensor)
Nikon calls all of their macro lenses to be a "Micro" lens, because they only go up to 1:1, but do not exceed it.
But that is purist any more, and no one else gives much attention to what they call macro. Some don't even reach 1:1. Hard to fight it, and even Nikon web site now groups all of their micro lenses under the heading of "macro lenses".