| Definition -
An expression X is said to have cumulative reference if and only if the following holds:
(1) If two separate entities can be said to be water, then combining them into one entity will yield more water. Hence, "water" has cumulative reference,
(2) However, if two separate entities can be said to be a house, their combination cannot be said to be a house. Hence, "a house" does not have cumulative reference
(3) However, while the expression a house does not have cumulative reference, the plural houses does, because if two entities are both houses, then their combination will still be "houses."