noun
20th day of the month
Refers specifically to the 20th day of a month. The reading はつか is irregular and must be memorized.
会議は来月の二十日です。
The meeting is on the 20th of next month.
二十日までにレポートを提出してください。
Please submit the report by the 20th.
noun
Indicates a duration of twenty days. The reading にじゅうにち is also possible but less common; はつか is the standard reading for this meaning as well.
この薬を二十日間飲み続けてください。
Please continue taking this medicine for 20 days.
二十日も雨が降り続いている。
It has been raining for 20 days straight.
Uncommon variant using the kanji 〇 for zero.
Archaic kanji form; rarely used in modern Japanese.
The reading はつか is a native Japanese (kun'yomi) reading for 二十日, combining 二十 (twenty) and 日 (day). The irregular sound change from ふたそか to はつか is a historical development.