This is more of an informative rant than anything but please bear with me here.
I have seen this term tossed about throughout the forum for some time and it just irks me. the fish most people refer to as "Fighter" is no longer considered a fighting fish. Let me explain why.
The history of the fighter. ( copied from The History of betta Fighting Fish
For the children of Malaysia, in southern China, collecting these Siamese fighting fish was a favorite pastime. The children would catch as many as 50 Bettas an hour from the rice paddies, and then conduct fish fights to determine the village champion. Usually, the winner was the biggest fish they caught. Once the wounds healed on the prize-winning fish, he would go into competition again against a new opponent. This pastime diminished significantly when agricultural chemicals and mechanized plowing were introduced for the harvesting of the rice paddies. However, the fields were not the only place where one could find Bettas. They were also living in watery ditches, stagnant ponds and gentle flowing streams.
Known as plakat, which means tearing or biting fish, the wild Bettas generally would have short-lived fights of only a few minutes. Nevertheless, once the Siamese started to breed them specifically for fighting, these matches could go on for hours. The winner was determined, not by the wounds he inflicted, but instead by his willingness to continue fighting. The losing fish retreated and the match was over. Destruction to the families of the men betting on the fish was also substantial, with potential losses as great as his money, his house, and on occasion, his wife or other family members!
Observing the obvious popularity of these fights, the King of Siam started licensing and collecting these fighting fish. In 1840, he gave some of his prized fish to a man who, in turn, gave them to Dr. Theodor Cantor, a medical scientist from Bangor. Describing these fish in an article nine years later, Dr. Cantor gave them the name Macropodus Pugnax. In 1909, Mr. Tate Regan renamed them Betta Splendens, noting that there already was a betta species with the name Dr. Cantor used. It is believed that Mr. Regan got the name from a warrior-like tribe of people named "Bettah".
These fish which were referred to are short finned. They were and are bred to fight.
Because these fish were so beautiful, people started to breed them for the beauty and then started to develop different strains. The veiltails were the first of the long finned varieties, followed by reduction in rays, or the crowntails, then the deltas, super deltas and finally halfmoon finnage. In all the varieties they have doubletails. These guys are in no way made for fighting, the finnage is too large and while they are aggressive to a point they are usually more domesticated than the fighters.
There are even less aggressive short finned plakats.
The difference in these and the fighters above is evident by not only the shape of the fish but the aggression level, and colorations. Fighters are bred for that, the breeder do not care the color, just that the teeth are sharp and scales are hard. The fighters are longer in the body for faster movement.