Junction (Electrical) Box - A square, octagonal, or rectangular plastic or metal box that fastens to framing and houses wires, and/or receptacles and/or switches.

Knockout - A removable piece of an electrical box or panel that's "knocked out" to allow cable to enter the box.
kVA - The kVA, or Kilovolt-ampere, output rating designates the output which a transformer can deliver for a specified time at rated secondary voltage and rate frequency without exceeding the specified temperature rise (1 kVA = 1000 VA)
kW - Kilowatts. Real power delivered to a load (W x 1,000 VA)

Lead - The short length of a conductor that hangs free in a box or service panel. (i.e. a wire end)
Load - The load of a transformer is the power, in kVA or volt-amperes, supplied by the transformer. Lagging Load: inductive type load. Leading Load: capacitive load.