Peng, Lu, Ji, An

Literally - ward off, rollback, press and push.

From Tai Chi Forms in the section called grasp the bird’s tail or grasp the sparrow’s tail.

The following videos are from a Chen Style master.

And a blog post from Graham Barlow probably going in to more detail than I probably wanted!

https://thetaichinotebook.com/2015/09/10/peng-lu-ji-an-grasping-the-birds-tail/

Postscript

Edited, 29-Aug-2024.

Peng, Lu, Ji and An are the first of the ‘four energies’. The remaining four are Tsai, Lieh, Zhou and Kao.

1. Ward-off: Peng corresponds to SKY, trigram yang yang yang.

2. Pull-back: Lu corresponds to EARTH, trigram yin, yin, yin.

3. Press: Ji corresponds to WATER, trigram yin yang yin.

4. Push: An corresponds to FIRE, trigram yang yin yang.

5. Grabbing (pull-down): Tsai corresponds to WIND, trigram yang yang yin.

6. Breaking (splitting): Lieh corresponds to THUNDER, trigram yin yin yang.

7. Elbowing: Zhou corresponds to LAKE, trigram yin yang yang.

8. Shouldering: Kao corresponds to MOUNTAIN, yang yin yin.

From https://taichinotebook.com/2014/11/15/eight-energies/