From the name of a river in Ireland. It is not clear why it has become so popular as a given name; compare Clodagh. In part it may also be a transferred use of the Irish surname, Gaelic Ó Seanáin ‘descendant of Seanán’ (a diminutive of Seán). Shannon is not found as a traditional given name in Ireland itself.
German: 1. from the East Prussian dialect word Keicher ‘small cake’, ‘pastry’, hence a metonymic occupational name for a pastrycook. 2. South German: from Middle High German kīchen ‘to gasp for breath’, hence a nickname for an asthmatic or someone perpetually out of breath. Compare Kaucher. 3. habitational name for someone from a place called Kaichen in Hesse.