The OIr. word for ‘adventure’, the first word in the title in a category of narrative that flourished from medieval to early modern times, especially during the 15th to 17th centuries. The thematic distinction of the Echtra is the setting of the hero's visit to the Otherworld; his journey, whether in a coracle or underground, is but a subordinate framework. The Echtra should be differentiated from stories beginning with the word Imram [voyage], which tell of the hero's voyage and adventures to an Otherworld located on islands in the western ocean. These adventurous tales became so popular that Echtra came to be used in the titles of any romance. Although titles of OIr. narratives are sometimes given ModIr. spellings, the ModIr. Eachtra lacks the specificity of Echtra and may be used in titles of comic or anti-heroic stories that do not follow earlier convention.
In the Echtra the hero is often enticed by a beautiful woman or wonderful warrior telling of the marvels of a mysterious land, where every pleasure may be had and illness, grief, old age, and death are unknown. To reach this land the hero must usually cross either the western ocean or a plain in which he is lost in a magic mist. When the invitation to visit the marvellous land comes from a wonderful warrior, he will be revealed to be a member of the Tuatha Dé Danann, the divine race of early Ireland, often Lug Lámfhota or Manannán mac Lir. Sometimes the hero never returns, but often he returns bearing gifts and great wisdom. The gravest danger facing the returning hero is that he will turn to dust as soon as his foot touches Ireland.
See David Dumville, ‘Echtrae and Immram: Some Problems of Definition’, Ériu, 27 (1976), 73–94.