Purnimanta
A lunar month ending at the full moon.
Used across the north. The month runs from the day after one full moon to the next. The consequence: the SAME dark fortnight carries a different month name in the two systems, one month apart. Krishna Paksha Chaturdashi of Phalguna (purnimanta) is Krishna Paksha Chaturdashi of Magha (amanta) — the same night, two names. This is the single most common source of 'my calendar says a different month' confusion, and neither is wrong.