There are multiple definitions - click on the translation that matches your context.

gromadzić się

czasownik

full

assemble

Definitions of assemble

to build something or to put something together from two or more parts

ALIGN desires to have ELAMEX assemble products in Mexico from parts, materials and certain equipment supplied by ALIGN

to come together as a group

Comic book fans are assembling in Peoria for Comic Expo.

to form a group from two or more people

The union board is assembling a "strike-preparedness committee".