An Irish ceremony/party held to celebrate/mourn the passing of a relative or friend over the Atlantic Ocean. This term derives from the period of mass emigration from Ireland in the second half of the nineteenth century. About a million Irish people emigrated following the Great Famine, and for most it was strictly a one way trip. To those left behind, the emigration of a loved one was akin to his/her death, as there was no prospect of ever seeing him/her again in this world.
For this reason, it became common to extend the same ceremonies to emigrants as to corpses, and a party in the form of a wake was held to see the emigrant off, and to help those left behind come to terms with their loss. This type of party became known as the American Wake.
Nowadays, of course, emigration is far from final, and the sense of loss is much dimmed as a result, but an emigrant's sending-off party is still sometimes facetiously referred to as his/her American Wake.