Sentence:  In B. M. Spinley 's portrayal of the underprivileged and undereducated youth of London , a salient finding was the <WSD>inability</WSD> to postpone gratification , a need to satisfy impulses immediately without the pleasure of anticipation or of savoring the experience . 
Meaning of the word marked with <WSD> tags:  lack of ability (especially mental ability) to do something