WordNet sense 1 (time need to prepare a vessel or ship for a return trip):

turnaround time

WordNet sense 2 (a decision to reverse an earlier decision):

flip-flop, reversal, turnabout, change of mind

WordNet sense 3 (act or process of unloading and loading and servicing a vessel or aircraft for a return trip):

turnround

WordNet sense 4 (turning in the opposite direction):

reverse, reversion