After looking for myself, the only electrical 'butted seam' I can find is in regards to the construction of the actual crimp-on connectors..
A butted seam here means that the… sleeve of the connector (where the wire goes) is not forged of one continuous piece of metal; rather, it is a flat piece of metal rolled into a cylinder, giving it a 'butted seam' where the two ends meet each other..
This is in comparison to a connector made with no seams, i.e. forged in a mold. etc. The connectors for high voltage/high amperage connections (like a pole mount transformer) are made solid like this..
I'd actually need to know in what context you heard that term..
Assuming you mean an electrical butt connection, that would be two wires connected at the ends by inserting each into an insulated butt connector, and crimping the connector onto both wires..
If this isn't what you mean, you would need to ask with context. Please update the discussion area for this question to add context, or ask a new question. ( Full Answer )