am·ni·o·cen·te·sis 
(ăm′nē-ō-sĕn-tēsĭs)
(ăm′nē-ō-sĕn-tēsĭs)n. pl. am·ni·o·cen·te·ses (-sēz)
A procedure in which a small sample of amniotic fluid is drawn out of the uterus through a needle inserted in the abdomen. The fluid is then analyzed to detect genetic abnormalities in the fetus or to determine the sex of the fetus.
[New Latin amniocentēsis : AMNION + Greek kentēsis, act of pricking (from kentein, to prick; see kent- in the Appendix of Indo-European roots).]