The best replacement for domains is workgroups.

The best alternatives to domains are rated as following:
★★★★★  workgroups
★★★★  kingdoms
★★  subdomains
★  broadcast domains
★  subunits
★  motifs
★  active directory
★  workgroup
★  collision domains
★  zones
  5 kingdoms
  domain names
  godaddy
  6 kingdoms
  urls
  parked domains

Your alternative for domains is not listed? Suggest!
Speaking about domains, one probably shouldn't forget about active directory.

Other search terms related to domains and their ratings are:
★★★★★ active directory
You have in mind a companion for domains and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of domains in all years. Click on graph for more.
domains
workgroups
kingdoms