There isn't a single, universally accepted synonym for "eukaryotes". However, depending on the context, you could use:

More general terms:

* Complex cells (emphasizes the structural complexity)

* Nucleated cells (refers to the presence of a nucleus)

* Organisms with nuclei (focuses on the nuclear feature)

More specific terms:

* Protista (if referring specifically to eukaryotic organisms that are not plants, animals, or fungi)

* Eukarya (the domain of life that includes all eukaryotes)

The best synonym to use will depend on the specific context and what you want to emphasize.