Traumatropism is the growth response to a wound.
Tropism is the growth response in all or part of a plant due to an external stimulus. Traumatropism in particular is the response to wounds or lesions (trauma-) and is mostly, if not entirely, comprised of negative traumatropism.
Negative traumatropism will cause the plant to move away from the wound.
Traumatropism is valuable for plants as it allows them to move away from the damaging stimulus.