also: デイ · ディ
Suffix attached to nouns to form names of special days, observances, or holidays. Often used in commercial or promotional contexts.
What will you give on Valentine's Day next month?
noun-modifying (irregular)
Prenominal element used in compounds to indicate something occurring during the day, as opposed to night. Most commonly seen in デーゲーム (day game).
See also: デーゲーム
This supermarket has a 'five-times-points day' on the 5th of every month.
At this store, every Friday is double points day.
Today's match is a day game, so don't forget to prepare for the heat.
birthday
Friday
Valentine's Day
day game; daytime baseball game
weekday
Most common spelling; used in many established compounds.
Alternate spelling, also common; often seen in loanwords.
Irregular kana usage; less common and may be considered non-standard.
Borrowed from English 'day'. The spelling デー reflects a long vowel adaptation, while デイ preserves the original diphthong. ディ is an irregular variant.