This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
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adj. Lasting for, extending over, or remaining during a night: an overnight trip; an overnight guest.

adj. For use over a single night or for a short journey: overnight supplies.

adj. Mailed for guaranteed delivery on the next day: an overnight package.

adj. Happening as if in a single night; sudden: an overnight success.

ad. During or for the length of the night: Let the meat marinate overnight.

ad. In or as if in the course of one night; suddenly: became a sensation overnight.

n. An overnight stay or trip.

verb-intransitive. To spend the night: overnighting at a country inn.

v. To send by mail or other courier for delivery the next day.

ad. Throughout the night

ad. During a single night

ad. In a very short (but unspecified) amount of time

adj. Occurring between dusk and dawn.

adj. Complete before the next morning.

n. Items delivered or completed overnight.

n. An overnight stay, especially in a hotel or other lodging facility.

n. The fore part of the night last past; the previous evening.

ad. In the fore part of the night last past; in the evening before.

ad. Throughout the night.

ad. During the night; hence, in a short period of time.

adj. Ocurring or accomplished during one night.

Through the night; during the evening or night; especially, during the night just passed.

n. Night before bedtime, referring to the night just passed.

Done or occurring overnight; specifically, in racing, noting an entry made just before the day of the race, or a race arranged ‘overnight.’

n. In racing, a race (or entry) arranged the night before it is run.

ad. during or for the length of one night

ad. happening in a short time or with great speed

adj. lasting, open, or operating through the whole night

"And of course 'overnight' is a relative term not unlike mañana."

long   

overnights   

Bright    Dwight    Knight    Night    White    Wight    Wright    alight    allright    alright   

fast    three-day    next    instantaneous    daily    yearly    permanent    four-hour    short-term    online