A transition adapter for terminating flat power cable includes at least a stamped and formed member having opposed plate sections between which an end or an edge portion of the cable is receivable to be terminated. The plate sections have opposing cooperating terminating regions comprised of a plurality of alternating wave shapes and relief recesses, with each wave shape aligned with a recess of the opposing terminating region. When the plate sections are urged together under sufficient force, shearing edges along each side of each wave shape shear the cable conductor by cooperating with shearing edges of the adjacent wave shape of the opposing terminating region, scissors-fashion. Crests of the wave shapes deflect the sheared cable portions into the opposing relief recesses, forming a series of interlocking wave joints across the intermeshing terminating regions and terminating the cable between the plate sections. The wave crests deflect integral strips of conductor out of the plane of the cable, exposing sheared conductor edges for electrical connection therewith such as with solder. Softer metal insert members may be secured to and along outer surfaces of the plate sections to engage and form gas-tight electrical connections with substantial surface areas of the sheared conductor edges.