What is the definition or description of: cervical thinning?

Cervix getting short: Cervical "thinning" is also called cervical effacement. In most women, the cervix is around 4-5cm long (0%). As the cervix ripens in preparation for labor it gets shorter. This is effacement. It is expressed as a percentage. Effacement continues during labor until it is 100% effaced (paper thin). This is one measurement labor staff use to track and communicate the progress of labor.