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The Collaborative International Dictionary of English v.0.48 (gcide)

Lightning \Light"ning\ (l[imac]t"n[i^]ng), n. [For lightening,
fr. lighten to flash.]
1. A discharge of atmospheric electricity, accompanied by a
vivid flash of light, commonly from one cloud to another,
sometimes from a cloud to the earth. The sound produced by
the electricity in passing rapidly through the atmosphere
constitutes thunder.
[1913 Webster]

2. The act of making bright, or the state of being made
bright; enlightenment; brightening, as of the mental
powers. [R.]
[1913 Webster]

{Ball lightning}, a rare form of lightning sometimes seen as
a globe of fire moving from the clouds to the earth.

{Chain lightning}, lightning in angular, zigzag, or forked
flashes.

{Heat lightning}, more or less vivid and extensive flashes of
electric light, without thunder, seen near the horizon,
esp. at the close of a hot day.

{Lightning arrester} (Telegraphy), a device, at the place
where a wire enters a building, for preventing injury by
lightning to an operator or instrument. It consists of a
short circuit to the ground interrupted by a thin
nonconductor over which lightning jumps. Called also
{lightning discharger}.

{Lightning bug} (Zool.), a luminous beetle. See {Firefly}.

{Lightning conductor}, a lightning rod.

{Lightning glance}, a quick, penetrating glance of a
brilliant eye.

{Lightning rod}, a metallic rod set up on a building, or on
the mast of a vessel, and connected with the earth or
water below, for the purpose of protecting the building or
vessel from lightning.

{Sheet lightning}, a diffused glow of electric light flashing
out from the clouds, and illumining their outlines. The
appearance is sometimes due to the reflection of light
from distant flashes of lightning by the nearer clouds.
[1913 Webster]


Lightning \Light"ning\ (l[imac]t"n[i^]ng), vb. n.
Lightening. [R.]
[1913 Webster]


electric current \electric current\, electrical current
\electrical current\,
the movement of electrically charged particles, atoms, or
ions, through solids, liquids, gases, or free space; the term
is usually used of relatively smooth movements of electric
charge through conductors, whether constant or variable.
Sudden movements of charge are usually referred to by other
terms, such as {spark} or {lightning} or {discharge}. In
metallic conductors the electric current is usually due to
movement of electrons through the metal. The current is
measured as the rate of movement of charge per unit time, and
is counted in units of amperes. As a formal definition, the
direction of movement of electric current is considered as
the same as the direction of movement of positive charge, or
in a direction opposite to the movement of negative charge.
Electric current may move constantly in a single direction,
called {direct current} (abbreviated {DC}), or may move
alternately in one direction and then the opposite direction,
called {alternating current} (abbreviated {AC}).
[PJC]