Testicle/ˈtestɪkl/ Definition 1 of 2Pro Tip 1/3Anatomical Term Used in medical or biological contexts to refer to male reproductive glands. The ultrasound showed his testicles were healthy. Pro Tip 2/3Sensitive Topic Conversations about testicles can be private or uncomfortable for some. He spoke quietly when discussing his testicle issue with the doctor. Pro Tip 3/3Gender Specific Relates only to males; females do not have testicles. Testicle development occurs in males during puberty.