Abortive means unsuccessful.
- The terrorist made an abortive attempt to blow up the bridge. (Their attempt to blow up the bridge was not successful.)
- I made an abortive effort to bake a cake yesterday. (My effort was not successful.)
- His attempt to climb the tree was abortive. He fell down when he was halfway up.
To abort something is to end it before it is completed.
We had to abort the vacation when dad fell ill.
To abort a pregnancy is to terminate it by bringing forth the fetus from the uterus before it is viable.