'shore' originates from Old English (Anglo-Saxon) words such as 'scora'/'sċor', from a Proto-Germanic root related to '*skur-' meaning 'cut, edge' or 'projecting piece of land'.

'shore' in Old English (e.g. 'scora'/'sċor') continued into Middle English as 'shore' and developed into the modern English 'shore'; the verb sense ('to support') developed later from the idea of a prop or support.

Initially it meant 'edge or bank of a body of water'; over time it retained that sense while also developing a verb sense meaning 'to prop up or support' and related figurative uses ('to shore up' = strengthen).