1590s, "unite or consolidate by hammering or compression, often after softening by heating," alteration of well (v.) "to boil, rise;" influenced by past participle form welled. Related: Welded; welding.
plant (Resedo luteola) producing yellow dye, late 14c., from Old English *wealde, perhaps a variant of Old English wald "forest" (see wold). Spanish gualda, French gaude are Germanic loan-words.
"joint formed by welding," 1831, from weld (v.).