anteanoche
the night before last
ante-
before
+
anoche
last night
Anteanoche means the night before last and can be thought of as ante-0 (before0) + anoche1 (last night1), literally meaning 'before last night'.
adverb
- the night before lastThe night before last nightAnteanoche tuvimos una cena familiar. // The night before last we had a family dinner.