Drone

Drone can refer to many things:

In music

A drone is a continuous note or chord.
A drone is also a part of some musical instruments (such as bagpipes) intended to produce such a continuous sustained pitch.
The drone, short for drone music, is a synonym for the music genre also known as dronology.

In nature

A drone is a male honeybee.

In fiction

A drone is a creature on the video game Halo and is insectoid in nature
A drone is a member of the Drones Club in P. G. Wodehouse's novels.
A drone is an unhappy citizen in the computer game Alpha Centauri
A drone is a humanoid assimilated by the Borg in the fictional Star Trek universe.
"Drone" is a 1998 episode from the fifth season of Voyager - See Star Trek Voyager episodes.
"Detective Drone" is the hero of Victorian crime stories
A drone is the worker unit for the zerg in Blizzard Entertainment's hit game, StarCraft and in other space games and fiction they are smallish robots that much like the honeybee do repetitive tasks and recon, in Eve online they are drones for seeing outside the ship and attacking enemies, drones or normally discreet and menacing in appearance.
A Drone is a weapon similar to a guided missile in the Stargate universe.
A drone is a humanoid-like (when not seemingly totally human) genetic created techno-creature in the "Panzer Dragoon" videogame series for Sega Saturn and Microsoft Xbox. The drones have a sole purpose or fate, and when they accomplish that mission they are "deactivated" by themselves, or have an automatic death. They also can be sleeping or hibernating for thousand of years, until they're required or awaken.

The best example of a "drone" is Azel, a female drone that looks like a normal girl, who starred "Panzer Dragoon RPG" (also called "Panzer Dragoon Saga" in the west), the third installment of the saga in the Saturn. Azel doesn't have any feelings or emotions at first, but eventually she will develop that kind of human sensations, including love. As a drone, she has the ability to communicate by telepathy with other beings, and with the ancient structures known only as "the towers". In the world of Panzer Dragoon, drones, monsters and dragons seems to have a common and mysterious origin, being placed in a strange planet that could be Mars in a distant future, or maybe in the past...

In many games a drone is a machine that acts as an ally and often has combat capabities. In some games, drones are companions, which follow the player's character around. In others, drones are considered a type of weapon and, once fired, will attract enemy fire and fire upon enemies, thus giving the player's character an increased probability of survival.
John Twelve Hawks' fictional novel 'The Traveller', describes drones as being citizens that have become exhausted and overwhelmed by the struggle of living and fight for survival; in a world controlled by the Tabula, who's plans are to control the entire human race by means of intense and intrusive electronic surveillance. Drones differ from the majority of 'ordinary citizens' by way of not being ignorant to the truth of what is happening outside of their own day-to-day lives.

In aviation

A drone is an unmanned aerial vehicle (UAV), often used for target practice, increasingly used for surveillance.

In nautics

A drone is a Remotely operated vehicle (ROV), used for mine clearing or underwater exploration.

References

The Taveller John Twelve Hawks Bantam Press 2005