also: やさか
noun
A somewhat literary or formal word for thriving and prosperity. Often used in celebratory contexts, such as toasts or well-wishes.
弥栄を祈念して乾杯しましょう。
Let's raise a glass to prosperity.
interjection
best of luck; hurray
Used as an exclamation to wish someone success or to cheer them on. Can be seen as a slightly old-fashioned or formal alternative to がんばって.
新しい門出に、弥栄！
Best of luck on your new journey!
The exact derivation is uncertain. The kanji 弥 (increasingly) and 栄 (glory/prosperity) combine to suggest ever-growing prosperity. The reading いやさか may be a native Japanese compound, with いや meaning 'more and more' and さか related to 栄える.