noun
19th day of the month
Refers specifically to the 19th calendar day. Used with dates, schedules, and deadlines.
会議は１９日に行われます。
The meeting will be held on the 19th.
このプロジェクトは１９日かかりました。
This project took 19 days.
noun
Archaic slang; not used in modern Japanese. The connection to the number 19 is unclear and may be based on old wordplay.
江戸時代の俗語で「じゅうくにち」は愚か者を指したらしい。
In Edo-period slang, 'juukunichi' apparently referred to a fool.
Compound of 十九 (nineteen) and 日 (day). The reading じゅうくにち is a regular combination of じゅうく (nineteen) and にち (day). The archaic slang sense is of uncertain origin.