Yielding

Yielding can mean: 

1. Stepping
2. Shifting the weight and turning the waist
3. Bowing the back and tucking in at the middle

Option 1 is favoured by baguazhang, although option 2 is acceptable.
Option 3 is a last ditch choice.

In tai chi, option 2 is favoured, with option 2 used as well.
Option 3 is not the preferred choice for tai chi.