Bridge verb

In syntax, a bridge verb is a verb which allows wh-movement out of its complement.

Examples
As shown by the grammaticality judgments in the sentence, say and think are examples of bridge verbs, while quip and whisper are not.

whoi did you think/say/*quip/*whisper [ that Bill saw ti]

Link
Utrecht Lexicon of Linguistics

Other languages

 * German: Brückenverb