- 1 [countable, uncountable] an act of injecting someone with a drug or other substance to give someone an injection He was treated with penicillin injections. An anesthetic was administered by injection. daily injections of insulin
- 2[countable] a large sum of money that is spent to help improve a situation, business, etc. The theater faces closure unless it gets an urgent cash injection.
- 3[uncountable, countable] an act of forcing liquid into something a fuel injection system