Freebase(0.00 / 0 votes)Rate this definition: Portable Network Graphics. Portable Network Graphics is a raster graphics file format that supports lossless data compression. PNG was created as an improved, non-patented replacement for Graphics Interchange Format, and is the most used lossless image compression format on the World Wide Web.
Definition of menopause. 1 : the natural cessation of menstruation that usually occurs between the ages of 45 and 55; also : the period during which such cessation occurs âcalled also climacteric â compare perimenopause. 2 : cessation of menstruation from other than natural causes.
Medical Definition of Menstruation. Menstruation: The periodic blood that flows as a discharge from the uterus. Also called menorrhea, the time during which menstruation occurs is referred to as menses. The menses occurs at approximately 4 week intervals to compose the menstrual cycle.