doubler

One who doubles.
An instrument for augmenting a very small quantity of electricity, so as to render it manifest by sparks or the electroscope.
A metal plate riveted or welded over a preexisting metal structural component to reinforce it and relieve the stress on the preexisting component, or to serve as a patch where part of the original structure has failed or been removed.
Part of a distilling apparatus for intercepting the heavier fractions and returning them to be redistilled.
A blanket or felt placed between the fabric and the printing table or cylinder.
A person employed in a roller mill to fold the hot metal plates in half.
A device with two electrical plugs that plugs into an electrical outlet, effectively converting the electrical outlet into two; socket converter.
A diaper insert.