Full Idea
Moore claims that 'right' means 'productive of the greatest possible good'.
Gist of Idea
For Moore, 'right' is what produces good
Source
report of G.E. Moore (Principia Ethica [1903]) by W. David Ross - The Right and the Good §I
Book Reference
Ross,W.David: 'The Right and the Good' [OUP 1930], p.8
A Reaction
Ross is at pains to keep 'right' and 'good' as quite distinct notions. Some actions are right but very unpleasant, and seem to produce no real good at all.