What is an antonym for the word morphing?

There isn't one perfect antonym for "morphing" as it depends on the context. Here are some possibilities, depending on what you want to emphasize:

If you mean changing form gradually:

* Staying the same

* Remaining static

* Being unchanging

* Maintaining form

If you mean changing form dramatically:

* Retaining

* Preserving

* Staying the same

* Retaining original form

If you mean changing form through special effects:

* De-morphing (this would be a technical term)

* Un-morphing

* Reverting

The best antonym for "morphing" will depend on the specific situation and the desired meaning.