The Rough Endoplasmic Reticulum (rER) is a cellular organelle responsible for protein synthesis and transport. It is covered in ribosomes which gives it the 'rough' appearance. There are several synonyms for rER such as granular endoplasmic reticulum, ergastoplasm, granular reticulum, and endoreticulum. These synonyms also refer to the presence of ribosomes on the rER. The rER works with the Golgi apparatus to modify and transport the proteins it creates. This organelle is essential for a variety of cellular processes and understanding its synonyms can aid in scientific communication and research.