urethra

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The canal through which urine is discharged from the bladder in most mammals and through which semen is discharged in the male.

Century Dictionary and Cyclopedia

1. n. A modification of a part of a urogenital sinus into a tube or a groove for the discharge of the secretion of the genital or urinary organs, or both; in most mammals, including man, a complete tube from the bladder to the exterior, conveying urine and semen in the male sex, urine only in the female; in some birds, a penial groove for the conveyance of semen only. The urethra of the male is always a part of the penis, or a penial urethra, continuous usually with the urethral part of the urogenital sinus; that of the female is only exceptionally a part of the clitoris. In man the urethra extends from the neck of the bladder to the end of the penis, usually a distance of 8 or 9 inches. It is divided into three sections. The prostatic is that first section of the urethra which is embraced by the prostatic gland, 1 ¼ inches long, somewhat fusiform; npon its floor is a longitudinal ridge, the veru montanum or caput gallinaginis, on each side of which is a depression, the prostatic sinus, perforated by openings of the prostatic ducts. In advance of the veru is a median depression or cul-de-sac, variously known as the vesicula prostatica, vagina masculina, sinus pocularis, uterus masculinus, etc.; and the orifices of the ejaculatory ducts of the seminal vesicles open here. The membranous is that second section of the urethra, about ¾ inch long, which extends from the prostatic gland to the corpus spongiosum; it is contracted in caliber, perforates the deep perineal fascia, and is embraced by layers reflected from this fascia and by the specialized compressor urethræ muscle. The spongy section of the urethra extends from the membranous section to the end of the penis, being all that part of the urethra which is embraced by the penial corpus spongiosum. It is dilated at its beginning—this dilatation being sometimes specified as the bulbous section of the urethra, and further marked by the opening of the ducts of Cowper's glands—and at its end, within the glans penis, this terminal enlargement being the fossa navicularis. The urethra ends in a narrow vertical slit, the meatus urinarius. Numerous submucous follicles, the glands of Littrė, open into the spongy section of the urethra; one of these openings forms a recess of considerable size, the lacuna magna. The substance of the urethra includes mucous, muscular, and erectile tissue. In the female the urethra is very short, about 1½ inches in length, and much more simple in structure and relations than that of the male.
2. n. the penis of any animal; in man, the spongy urethra.

Wiktionary

1. n. anatomy The tube through which urine exits the body and, in males, through which semen is ejaculated.

GNU Webster's 1913

1. n. (Anat.) The canal by which the urine is conducted from the bladder and discharged.

WordNet 3.0

1. n. duct through which urine is discharged in most mammals and which serves as the male genital duct