1 [intransitive and transitive]
to form a group again in order to be more effective, or to make people do this:
The Allies regrouped and launched a new attack.
The Russians retreated, needing to regroup their forces.
2 [intransitive] American English
to stop and think about something, so that you can start to do something again in a better way:
I paused for a minute to regroup.