Constant in a quantity that does not vary, e.g. in formula pV=RT, R is a universal constant and is equal to 8.314 J mol-1 K-1, while p, V and T are variables.
Citing this page:
Generalic, Eni. "Constant." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.