BT San 18b(42) :וסמכו רבנן אחושבניהו‏ : the scholars relied on their (own) reckoning (concerning the intercalary month)
See the entire entry for ḥušbān, ḥušbānā n.m. calculation

BT San 18b(42) :ועברוה לההיא שתא‏ : they intercalated that year
See the entire entry for ˁbr vb. to cross over

BT San 18b(42) :ועברוה לההיא שתא‏ : they intercalated a month of that year
See the entire entry for šnā, šattā n.f. year