Noun
tactus (uncountable)
The sense of touch.
By the 16th century, the tactus was generally two semibreves per breve, with three per breve used for special effects and climactic sections. Source: Internet
It was in the opening decades of the next century that music felt in a tactus (think of the modern time signature) of two semibreves-to-a-breve began to be as common as that with three semibreves-to-a-breve, as had prevailed prior to that time. Source: Internet