noun, feminine/kɑ̃.ti.te ne.ɡli.ʒabl/plural: quantités négligeables
something that doesn't enter the equation, something or someone that is deemed negligible, i.e. so insignificant that it or they can be ignored
“tenir quelqu'un en quantité négligeable, tenir quelqu'un comme quantité négligeable” — to not take someone and their opinion into account, to disregard someone and ignore their opinion
Literally, “negligible quantity”. Compare English unknown quantity.