overwatch verb 3noun 1forms 4 verb3 •To watch over. •To watch excessively. •(no longer used) To overcome with long lack of rest. noun1 •The supervision of one unit or vehicle by another while the supervised unit is firing or moving.At a further and undefined point in the future, the American force would shrink to about seven and later five brigades — all involved in overwatch missions. — 2007 formsoverwatch'd · overwatched · overwatching · overwatches