ward off
To push back or defend against someone or something that is advancing. A noun or pronoun can be used between "ward" and "off." How will we ward off all these attackers? If you feel like you're getting a cold, these vitamin C tablets should help you to ward it off. These talismans were thought to ward off evil spirits.
ward someone or something off
to hold someone or something off; to fight someone or something off. The army was able to ward the attackers off repeatedly. We couldn't ward off the attackers any longer.
ward off
1. Turn aside, parry, as in He tried to ward off her blows. [Second half of 1500s]
2. Try to prevent, avert, as in She took vitamin C to ward off a cold. [Mid-1700s]
ward off
v.1. To try to prevent; avert: You should take vitamins to ward off infections.
2. To turn something aside; repel: The champion boxer warded off the opponent's blows. The flies were annoying me, but I warded them off.