also: こうかいび
release date; publication date; opening day
Refers to the date when something becomes publicly available, such as a movie, game, book, or event. Can also mean the first day a facility or service opens to the public.
The release date for the new movie is Friday next month.
この美術館の公開日はまだ決まっていません。
The opening day of this museum hasn't been decided yet.
開設日 refers to the establishment or founding date of an organization, facility, or system, often with a more formal or administrative nuance than 公開日.
Standard kanji spelling. The reading こうかいび is more common than こうかいひ.
Alternate reading; less common but still used.
Compound of 公開 (こうかい, 'public opening, release') and 日 (ひ/び, 'day'). The reading こうかいび is a standard rendaku (sequential voicing) form.