Entomology definition of Sienna September 13, 2014 Raj Entomology Dictionary 0 Please Like Us!!! DesiGoogly.com > Education News > Entomology Dictionary > Entomology definition of Sienna Entomology definition of Sienna: a brownish orange [brown ochre]. Entomology Sienna definitionSienna Entomology explanationSienna Entomology meaningReviews & Comments