Can a lilac bush cut down to the ground grow back?

Yes, a lilac bush that is cut down to ground level can grow back. Lilac bushes (Syringa spp) number among the woody plants that survive extreme, rejuvenation and severe pruning every three to five years. They tend to grow back, even when their trunks split right down the middle, unless accidental or deliberate, human- or Nature-inflicted trims take place during such moisture events as hail, rain, sleet and snow storms since few bushes, shrubs and trees handle wet weather event-launched cankers.