The Óenach, usually translated fair or assembly, was an annual gathering in Ireland which combined features of the popular assembly and fair. As well as the entertainment, the óenach was an occasion on which kings and notables met under truce and where laws were pronounced and confirmed.
The most notable fair, that held under the auspices of the High King of Ireland and the Uí Néill, was the Óenach Tailten, which is given prehistoric origins by medieval writers. This was held at Teltown, in modern County Meath, as late as 1770. The compilers of the Irish annals considered violence and disorders at this óenach, or the failure of the incumbent High King to hold the fair, to be of note.
Other important assemblies included that of Tlachtga, held on the Hill of Ward at Samhain, that of Carman, held in County Wexford, and that of Uisnech, held at Beltane. Not all had such pagan associations. The Óenach Colmáin, probably held at Lynally, was named for Saint Elo Colman.