flow rate

of a quantity
https://doi.org/10.1351/goldbook.F02441
Quantity X (e.g. heat, amount, mass, volume, ...) transferred in a time interval divided by that time interval. General symbols: qX, X.
Source:
Green Book, 2nd ed., p. 65 (https://dev.goldbook.iupac.org/files/pdf/green_book_2ed.pdf)