What sort of disorder is an ectopic pregnancy?

Ectopic Pregnancy. A pregnancy which is developing outside of the uterus is an ectopic pregnancy. Most commonly it is in the fallopian tube.
Wrong place. An ectopic pregnancy is when the embryo is implanted in a place where it shouldn't be, for example outside of the uterus, most commonly in the fallopian tube.

Related Questions

Is pelvic inflammatory disease associated with ectopic pregnancy?

Yes. Because it can damage fallopian tubes.
Yes. Pid is one of the strongest risks for ectopic pregnancy, because tubal damage is one of the hallmarks of pid.