ETYM Old Eng. fifte, fifthe, AS. fîfta. Related to Five.
Coming next after the fourth and just before the sixth in position; SYN. 5th.

Množina: fifth columns

A subversive group that supports the enemy and engages in espionage or sabotage; an enemy in one's midst; SYN. Trojan horse.
Group within a country secretly aiding an enemy attacking from without. The term originated 1936 during the Spanish Civil War, when General Mola boasted that Franco supporters were attacking Madrid with four columns and that they had a “fifth column” inside the city.

Množina: fifth generations

Množina: fifth-generation computers

Anticipated new type of computer based on emerging microelectronic technologies with high computing speeds and parallel processing. The development of very large-scale integration (VLSI) technology, which can put many more circuits on to an integrated circuit (chip) than is currently possible, and developments in computer hardware and software design may produce computers far more powerful than those in current use.
It has been predicted that such a computer will be able to communicate in natural spoken language with its user; store vast knowledge databases; search rapidly through these databases, making intelligent inferences and drawing logical conclusions; and process images and “see” objects in the way that humans do.
In 1981 Japan’s Ministry of International Trade and Industry launched a ten-year project to build the first fifth-generation computer, the “parallel inference machine”, consisting of over a thousand microprocessors operating in parallel with each other. By 1992, however, the project was behind schedule and had only produced 256-processor modules. It has since been suggested that research into other technologies, such as neural networks, may present more promising approaches to artificial intelligence. Compare earlier computer generations.