noun, adverb
month before last
Refers to the month two months before the current month. Often used with time expressions like の or as an adverb.
先々月、京都に行きました。
I went to Kyoto the month before last.
先々月の請求書が見つからない。
I can't find the invoice from the month before last.
Standard kanji spelling with iteration mark.
Alternate spelling without iteration mark; less common but still used.
Compound of 先 (previous) reduplicated with the iteration mark 々, plus 月 (month). The reduplication indicates 'two steps back' in time.