Similar to a collection of Hapax Legomena, this library collects abbreviations that form a word* and occur only once in either the whole Tanakh or only the Torah, either as acronym—here: abbreviation of first letters—or bacronym—abbreviation of last letters.

* in Biblical Hebrew/Aramaic or Modern Hebrew; all forms: basic, declined, male, female, singular, plural, with or without prefix/suffix; even existing acronyms that entered the dictionary