1) Electronic device 
Mating pair of crabs
• (n.) An instrument for augmenting a very small quantity of electricity, so as to render it manifest by sparks or the electroscope. • (n.) One who, or that which, doubles. • (n.) A part of a distilling apparatus for intercepting the heavier fractions and returning them to be redistilled. • (n.) A blanket or felt placed between ...
A male crab carrying a sexually mature female underneath him; a pair of mating crabs; buck and rider or carrier.
The pot still used for second distillation, where batch distillation is used.
A second sheet of material fixed inside the main fuselage side sheets on each side For added strength
Dou'bler noun 1. One who, or that which, doubles. 2. (Electricity) An instrument for augmenting a very small quantity of electricity, so as to render it manifest by sparks or the electroscope. 
Extra layers of reinforcement for added stiffness or strength in laminate areas that incur abrupt load transfers.
A second pot still used for a second distillation.
Doubler is slang for an extremely severe blow.
A type of pot still for second distillation that amps up the ABV.
noun an electronic device that doubles the voltage or the frequency of an input signal
The pot still used for the second distillation, where batch distillation is used.
Copper kettle downstream of a column distillation.