Back-formation from hossza (“its length”), the 3rd-person possessive form of hosszú (“long”, [obsolete] “length”); for its word-final vowel alternation ú ~ a, compare borjú → borja and others. Created during the Hungarian language reform, which took place in the 18th–19th centuries, from phrases like egyhosszában (“in a row”, rare; synonym of egyvégtében), se vége, se hossza (“[there is/was] no end to…”).