"Geas" and "Geasa" redirect here. For the heavy metal band, see Geasa In Irish mythology and folklore, a geis (//, plural geasa) is an idiosyncratic taboo, whether of obligation or prohibition, similar to being under a vow or spell. Geasa in Irish Mythology A geis can be compared with a curse or, paradoxically, a gift. If someone under a geis violates the associated taboo, the infractor will suffer dishonour or even death. On the other hand, the observing of one's geasa is believed to bring power and good fortune. Often it is women who place geasa upon men. In some cases the woman turns out to be goddess or other sovereignty figure.MacKillop, James (1998) A Dictionary of Celtic Mythology. Oxford, Oxford University Press. ISBN 0-19-280120-1 p.249 The geis is often a key device in hero