Non credo esista una traduzione. Si tratta di un termine coniato in Gran Bretagna negli anni '60.
Lo lascerei in inglese spiegando di cosa si tratta.

"An Awayday is the term used in British business for a meeting, often of a whole department, project or sales team, which takes place off-site and away from the participants' regular office surroundings, usually for a whole day or sometimes a weekend. It may, however, refer to a within-day meeting in a windowless room on-site.

The intention is to allow the meeting to focus on the particular task at hand without the participants being distracted by the demands which, if the meeting were held in the workplace, would normally be made on their attention by virtue of their positions.

The term derives from the name given to a cheap day return railway ticket (a substantially reduced two-way fare for off-peak travel) after pricing by time of travel was introduced on the British railway network in the 1960s".

http://en.wikipedia.org/wiki/Awayday

È un incontro lavorativo al di fuori dell'ambiente aziendale.

Dove ho lavorato questi raduni (sia in sede che fuori, a volte n altre città, a volte di un giorno o più giorni) li ho sempre sentiti chiamare così.
A volte anche "convention aziendale"