I. ham ‧ string 1 /ˈhæmˌstrɪŋ/ BrE AmE noun [countable]
a ↑ tendon behind your knee, which sometimes gets injured when you do sport:
He pulled a hamstring in training.
hamstring injury/problem/strain etc
II. hamstring 2 BrE AmE verb ( past tense and past participle hamstrung /-strʌŋ/) [transitive]
to make someone unable to take the action they want or need to take, especially by restricting them:
The President feels he is hamstrung by Congress.