bare infinitive
noun [ C ] language specialized uk/ˌbeər ɪnˈfɪn.ɪ.tɪv/ us/ˌber ɪnˈfɪn.ə.t̬ɪv/
不带 to 的动词不定式
in grammar, the infinitive form of a verb without the word "to"
In the sentence "I let him go", the bare infinitive is the word "go". 在句子 Let her go 中，go 就属于不带 to 的动词不定式。