Huí huáyīn 回滑音 “Returning Slide”

The general term for a slide from one pitch to a second and then back. Kao offers two with this name:

Huiyin 1: Pluck a string, press it in with the left hand, and then relax the left hand, creating an up-down slide.

Huiyin 2: Pluck a string, press it in with the left hand, relax the left hand, and then press it again, creating an up-down-up slide. May be abbreviated to just huí 回.