あいづち responding during conversation
言葉の語源 kotoba no gogen - The origin of words:
あいづち aizuchi [相槌]
Meaning: verbal or non verbal responses of agreement while someone is speaking. (While listening to someone you nod for example)
Hint: Remember the "zu" is づ
aizuchi o utsu
ano hito no hanashi wa omoshiroku nakatta keredo, ichiou aizuchi o uchinagara kiiteita
That person's story wasn't interesting, but I listened while throwing in the occasional "uh huh" or "yes."
kurei san wa "sou desu ne" to aizuchi o uchimashita.
Clay agreed with a nod of "that's right".
Origin: This word comes from the conversation-like pounding when making swords. Sword makers would use a hammer called つち （槌） to pound the molten metal into the right shape. Several people would take turns pounding in a rhythm as if conversing with each other but without words. From this came the meaning of responding to someone non verbally while speaking.