Ma'anar ƙamus na kalmar "shekara bissextile" tana nufin shekara ta tsalle, wato shekara ce da aka ƙara ƙarin rana a cikin kalanda domin a daidaita ta da shekarar hasken rana. Wannan karin rana da aka kara da watan Fabrairu, ta sanya shekara ta tsawon kwanaki 366 maimakon kwanaki 365 da aka saba yi. Kalmar "bissextile" ta fito ne daga kalmar Latin "bis sextus," wanda ke nufin "sau biyu na shida," domin ana maimaita rana ta shida kafin ƙarshen Fabrairu (24 ga Fabrairu) sau biyu a cikin shekara ta tsalle.