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antigestational drug

American  
[an-tee-jes-tey-shuh-nl, an-tahy‑] / ˌæn ti dʒɛsˈteɪ ʃə nl, ˌæn taɪ‑ /

noun

  1. a drug that averts a pregnancy by preventing the fertilized egg from becoming implanted in the uterine wall.