Trimer may refer to:
Trimer (chemistry), a reaction product composed of three identical molecules Protein trimer, a compound of three macromolecules non-covalently bound Efimov trimer, a weakly bound quantum mechanical state of three identical particles Trimer, Ille-et-Vilaine, a commune in France
See also Trimery (botany), having three parts in a distinct whorl of a plant structure Trimerus, Latin name of the Tremiti Islands, Italy tri, a prefix -mer, an affix Trimmer (disambiguation)