soliton

https://doi.org/10.1351/goldbook.ST07101
Localized excitations propagating in a system with constant velocity and colliding with each other without change in their shapes.
Source:
PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 422 (https://doi.org/10.1351/pac200779030293)