おめでとう

Etymology 1
→ →  →

Originally a compound of, from adjective.

Modern Japanese -i adjectives formerly ended in -ki for the attributive form. This medial dropped out during the, both for the attributive form (-ki becoming -i) and for the adverbial form (-ku becoming -u). However, the adverbial form reverted back to -ku thereafter for most words, with the -u ending persisting in certain everyday set expressions, such as arigatō, ohayō, or omedetō, and in hyper-formal speech.

Interjection

 * 1) congratulations, congrats

Usage notes
Most often written in hiragana. May occasionally be seen spelled in kanji, generally for more formal writing. The kanji spellings are examples of ateji. Usually followed by in less casual contexts.

Derived terms

 * : congratulations
 * : happy New Year
 * : happy birthday

Etymology 2
A pun on the congratulatory meaning of omedetō, using the common kanji spelling of 御目出 for the omede- portion and spelling the final -tō with the character.

Noun

 * 1)  a type of Japanese sweet made from rice and azuki bean paste, eaten at times of celebration