1. noun /ˈkwɒntəm,ˈkwɑn(t)əm/
a) Quantity, amount.
The reader will perhaps be curious to know the quantum of this present, but we cannot satisfy his curiosity.
b) The smallest possible, and therefore indivisible, unit of a given quantity or quantifiable phenomenon.
The Congresss core ministerial panel on Friday gave its green signal to raising motor fuel prices but the quantum of increase emerged as a hitch.
See Also: quantize
2. adjective /ˈkwɒntəm,ˈkwɑn(t)əm/
a) Of a change, significant
b) Involving quanta
Wikipedia foundation.