An Etymological Dictionary of Astronomy and Astrophysics

The property of magnitude.
An entity having magnitude, size, extent, or amount.

Etymology (EN): M.E., from rom O.Fr. quantite (Fr. quantité), from L. quantitatem (nominative quantitas), from quant(us) “how much?” + -itas, → -ity.

Etymology (PE): Candâ, candi “quantity,” Mid.Pers. candih “amount, quantity,” from cand “how many, how much; so many, much;” O.Pers. yāvā “as long as;” Av. yauuant- [adj.] “how great?, how much?, how many?,” yauuat [adv.] “as much as, as far as;” cf. Skt. yāvant- “how big, how much;” Gk. heos “as long as, until.”