Which Hebrew term names the Passover-eve fast observed by firstborn Jews?

Which Hebrew term names the Passover-eve fast observed by firstborn Jews? The term is Ta’anit Bechorot, also written Ta'anit Bekhorot or Ta’anit Bechorim. It names the Fast of the Firstborn, traditionally observed on the day before Passover, 14 Nisan.

The fast commemorates the survival of Israelite firstborns during the biblical Plague of the Firstborn. Unlike Yom Kippur and Tisha B’Av, it is generally treated as a customary fast rather than one of the Torah’s explicitly named full fast days. In common practice, firstborns often attend a siyum, a celebratory completion of Torah or Talmud study, and eat at the associated meal.

The spelling varies because Hebrew is being transliterated into English, so Ta’anit Bechorot and Ta’anit Bekhorot refer to the same observance. It should not be confused with Tzom Gedaliah, which commemorates the assassination of Gedaliah, or Tisha B’Av, which mourns major disasters including the destruction of the Temples.