Expressions (phrases, clauses, etc.), Godan verb with 'tsu' ending
to make use of aizuchi; to back-channel; to throw in interjections to show that one is paying attention
「私もそう思うわ」と彼女は相づちを打った。"I think so, too," she chimed in.
Also written 相づちを打つ【あいづちをうつ】、あいづちを打つ【あいづちをうつ】