Ma'anar ƙamus na kalmar "Yatsan hannu" ita ce yatsa kusa da babban yatsan hannu, musamman ma a hannun dama, wanda ake amfani da shi wajen nuna abubuwa ko kuma nuna wani matsayi ko alkibla. Ana kuma san shi da ɗan yatsa ko mai nuni. Babban yatsan yatsan yatsa shine mafi ƙwaƙƙwaran duk yatsu kuma ana amfani dashi don ayyuka daban-daban, gami da bugawa, rubutu, da kama ƙananan abubuwa.
