Full Idea
'Yellow' and 'water' are mass terms, concerned only with spread; 'apple' and 'square' are terms of divided reference, concerned with both spread and individuation.
Gist of Idea
Mass terms just concern spread, but other terms involve both spread and individuation
Source
Willard Quine (Natural Kinds [1969], p.124)
Book Reference
Quine,Willard: 'Ontological Relativity and Other Essays' [Columbia 1969], p.124
A Reaction
Would you like some apple? Pass me that water. It is helpful to see that it is a requirement of 'individuation' that is missing from terms for stuff.