They called it a comet, 'for lack of' a better term/word. [=because they could not think of a better term/word for it]
His honesty, or 'lack thereof', is the real problem. [=the real problem is his lack of honesty]
There was 'no lack of' interest in the proposal. [=there was much interest in the proposal]
(..) ...and it can only be achieved when there is no one left to oppose us. - But the Guardians... - The Guardians know this. But their collective minds lack the singularity to do what must be done. You can help me, Laira. With the power in your grasp, no one will be able to stand in our way. (..)2011 Green Lantern: Emerald Knights