if you are brave, Google. Is a glob (literally) of thick sticky mucus that forms inside the cervix to act as a plug, so to speak. This regenerates over time if you lose bits and pieces. they say if lose your plug you will go into labor soon but this is not true. there are many reasons you may lose it. Just one of those reasons is because you have began to dilate and efface but that does not mean you ate quickly dilating either.