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]
(..) Am I? It's in your nature. Your heroes are scattered. Your floating fortress falls from the sky. Where is my disadvantage? You lack conviction. I don't think I'm... So, that's what it does. Cap, hit the lever. I need a minute here! Lever (..)2012 The Avengers