The term "evergreen" refers to the release strategy. Evergreen browsers are updated frequently (Microsoft Edge Changelog, Firefox Release Calendar, Chrome Release Schedule) in background, constantly updating their compliance with Web Standards and also adding proprietary features.
The version of an evergreen browser (e.g. Microsoft Edge) lost its importance, because an evergreen browser is expected to run on the most recent version.
NEW MUC Airport Workshop: Migrating Java Client (Swing / Java FX) to Web Standards