'weld' originates from Middle English, specifically the word 'welden', where the element 'wel-' is associated with heating or melting (ultimate origin uncertain).

'weld' changed from Middle English 'welden' (or variants such as 'welden'/'weldenn') and eventually became the modern English word 'weld' through regular simplification of endings.

Initially, it meant 'to heat or melt (metal) in order to join pieces together,' and over time it has retained that core meaning while also gaining some extended, figurative senses of 'joining closely.'