noun
29th day of the month
Refers specifically to the 29th day of a month. The reading にじゅうくにち is the most common, but にじゅうきゅうにち is also acceptable.
会議は２９日に行われます。
The meeting will be held on the 29th.
２月２９日はうるう日です。
February 29th is a leap day.
noun
29 days
Used when counting a period of 29 days, not a date. Often appears with counters or in duration expressions.
この薬は２９日分あります。
This medicine is for 29 days.
２９日間の旅行でした。
It was a 29-day trip.
Abbreviated kanji spelling; rarely used in modern Japanese.
Compound of 二十九 (にじゅうく, twenty-nine) and 日 (にち, day). The reading にじゅうくにち is the standard, while にじゅうきゅうにち is a less common variant.