aber

Aber is a Welsh toponymic element meaning "river mouth" or "estuary" and is used in place names to mark the location where a river meets the sea or tidal waters. It is a stable term in Welsh geography and placenames, conveying a sense of the river’s entry point into larger bodies of water.

The term originates in Welsh and derives from the Brythonic branch of the Celtic language family; it is preserved in modern Welsh toponymy and is a common prefix in coastal and riverine place names. In English-language contexts in Wales, the form is typically retained as part of the place name.

Examples include Aberystwyth (mouth of the Ystwyth), Abergele (mouth of the Gele), Aberavon (mouth of the Avon), Aberaeron (mouth of the Aeron), and Abergavenny (mouth of the Gavenny). These names illustrate how "aber" signals a river’s entry point, whether at the sea or a tidal estuary, and sometimes at a confluence inland.

The element remains a standard feature of Welsh geography and historical records; in English-language writing it is often preserved in a fixed form as part of the placename. See also Welsh language, toponymy, and Welsh placenames.