Entomology definition of Trigonal September 14, 2014 Raj Entomology Dictionary 0 Please Like Us!!! DesiGoogly.com > Education News > Entomology Dictionary > Entomology definition of Trigonal Entomology definition of Trigonal: triangular: an area bounded by a triangle. Entomology Trigonal definitionTrigonal Entomology explanationTrigonal Entomology meaningReviews & Comments