1) Amalgamate 2) Amalgamated 3) Became one 4) Coalesced 5) Combined by melting 6) Consolidated 7) Formed a more perfect union 8) Joined by heating 9) Joined by melting 10) Joined together into a whole 11) Like sacral vertebrae 12) Liquefied 13) Made into an alloy 14) Melded 15) Melded together 16) Melted Found on https://www.crosswordclues.com/clue/fused