Heads up' is an idiom used to warn someone of an impending danger or to ALERT them to pay attention. The crossword solutions for this term include 'ALERT, ' 'LEADS, ' 'FORE, ' 'RUNS, ' 'SMART, ' 'SOARS, ' 'CHAIRS, ' 'CLIMBS, ' 'ASCENDS, ' 'AVIATES, ' 'WARNING, ' 'watchout, ' 'thinkfast, ' 'advancenotice, ' 'climbsamountain, ' 'cointossresults, ' 'leadsacommittee, ' and 'warningofdanger.' All of these words are related to the idea of being aware of a potential danger or taking action in order to prevent it.