Newton referred to this as a fluxion. (See Article 567 of Florian Cajori's book on A History of Mathematical Notations) Isaac Newton 's
Kaynak: Newton's notation

In the Methodus Fluxionum he defined the rate of generated change as a fluxion , which he represented by a dotted letter, and the quantity
Kaynak: History of calculus

laid the foundation for a complete system of fluxion s ... and their works ... abound with fluxional forms and series to be found in no
Kaynak: C. M. Whish