trim·er·ous \ˈtrimərəs\adjective Etymology: New Latin trimerus, from Greek trimerēs of three parts, from tri- three + meros part — more at tri-, merit 1.: having the parts in threes — used of a flower and often written 3-merous 2.of an insect a.: having three or apparently three segments in each tarsus b.: belonging to the Pseudotrimera