Azoospermia: Refers to extremely low or nonexistent levels of sperm in semen. Azoospermia is not synonymous with infertility; a biological child is possible with the help of a sperm harvesting procedure.
Follicle-stimulating hormone (FSH): A key part of reproduction for men and women. In men, it stimulates and sustains sperm production. An endocrinologist would be especially concerned about FSH levels when investigating infertility.
Luteinizing hormone (LH): A hormone produced by the pituitary gland, also present in men and women, and also of particular concern to an endocrinologist. In men, LH is responsible for initiating testosterone production.
Reproductive endocrinologist (RE): An ob-gyn who specializes in reproductive endocrine disorders and infertility. REs do not just treat female infertility, they also run tests on male infertility.
Retrograde ejaculation: When semen enters the bladder during ejaculation instead of exiting through the urethra.
Semen analysis: The microscopic examination of sperm that helps determine (1) sperm count, (2) morphology, or sperm shape, and (3) motility, or how well the sperm move.
Testicular sperm extraction (TESE): A minor surgical procedure that involves removing a small sample of testicular tissue in order to collect sperm for use in an in vitro fertilization (IVF) cycle.
Testosterone: A male sex hormone. It is produced in the testicles and helps with sperm production.
Urologist: A medical doctor who specializes in the treatment of disorders and diseases related to urinary organs (both male and female) and male reproductive organs.
Varicocele: Just one cause of male infertility. It occurs when varicose veins are present in blood vessels above the testes.
A glossary cannot provide every answer for you when you are exploring the confusing time of questioning fertility, but that is what fertility experts are for. Reproductive centers have astounding technology nowadays that give you plenty of fertility options.