Phrase(s): wave back (at someone)
to return someone’s hand signal of greeting. • I waved back at her, but she didn’t see me. • She didn’t wave back., Phrase(s): wave someone back (from something)
to motion someone to move back from something. • The police officer waved the curious onlookers back from the scene of the crime. • The students started to go onstage, but the teacher waved them back.
McGrawhill's American Idioms And Phrasal Verbs