Academus (or Hecademus, Greek: Akademos or Hekademos) was an Attic hero, whose garden was selected by Plato for the place of his lectures. Hence his disciples were called the "Academic sect."

Academy - The Academia was originally a public garden or grove in the suburbs of Athens, about six stadia from the city, named from Academus, who left it to the citizens for gymnastics. It was surrounded with a wall by Hipparchus, adorned with statues, temples, and sepulchres of illustrious men; planted with olive and plane trees, and watered by the Cephisus. The olive-trees, according to Athenian fables, were reared from layers taken from the sacred olive in the Erechtheum, and afforded the oil given as a prize to victors at the Panathenean festival. The Academy suffered severely during the siege of Athens by Sylla, many trees being cut down to supply timber for machines of war. Few retreats could be more favorable to philosophy and the Muses. Within this enclosure Plato possessed, as part of his patrimony, a small garden, in which he opened a school for the reception of those inclined to attend his instructions. Hence arose the 'Academic sect,' and hence the term Academy has descended to our times.

Academy (from Encyclopedia Britannica online) - Greek ACADEMEIA, Latin ACADEMIA, in ancient Greece, the academy, or college, of philosophy in the northwestern outskirts of Athens, where Plato acquired property about 387 BC and used to teach. At the site there had been an olive grove, park, and gymnasium sacred to the legendary Attic hero Academus.

Academus had owned the property in the time of Theseus, and the cult dedicated to him dates back to at least the earliest years of the sixth century. It was Academus who revealed to the Dioskouroi where Theseus had hidden Helen of Troy. Because of Academus's actions, the Dioskouroi honoured Academus, and the Spartans would not ravage the groves out of respect when they invaded Attica.

The term "Akademeia" does not admit to exact definition. Ancients used it not only to identify Platon's school but the area enclosed by the precinct wall as well as the surrounding area. Originally, the land was arid, but the statesman Kimon made it into a well-watered grove, building running tracks and shady walks, and the original name for this entire region was Hekademeia (graph and following information from Christopher's Plato site).

The designation academy, as a school of philosophy, is usually applied not to Plato's immediate circle but to his successors. Legally, the school was a corporate body organized for worship of the Muses, the 'scholarch' (or headmaster) being elected for life by a majority vote of the members. Most scholars infer, mainly from Plato's writings, that instruction originally included mathematics, dialectics, natural science, and preparation for statesmanship. The Academy continued until AD 529, when the emperor Justinian closed it.

The Academy philosophically underwent various phases, arbitrarily classified as follows: (1) the Old Academy, under Plato and his immediate successors as scholarchs, when the philosophic thought there was moral, speculative, and dogmatic, (2) the Middle Academy, begun by Arcesilaus (316/315-c. 241 BC), who introduced a nondogmatic skepticism, and (3) the New Academy, founded by Carneades (2nd century BC), which ended with the scholarch Antiochus of Ascalon (d. 68 BC), who effected a return to the dogmatism of the Old Academy. Thereafter, the Academy was a centre of Middle Platonism and Neoplatonism until it was closed in the 6th century AD.

The site of the Academy was discovered by archaeologists in 1930. In 1997, the Greek Government announced the creation of an urban park running from the Acropolis, through the Agora, the Keramikos cemetery (Plato’s apparent resting-place), the columns of Olympian Zeus, and the Olympic stadium, all the way to the site of Plato’s Academy. 

English teacher Carla Beard's website Calliope on English words derived from classical mythology gives a very illuminating explanation of academics, also in relation to sports and school (see Calliope site).

In the outskirts of Athens there was a park dedicated to the hero Academus, and it was used for gymnastics. Plato acquired part of the land in about 387 B.C., and used it as a school for those wishing to attend his lessons. He advocated skepticism, questioning, free thought, and, of course, the Socratic method. Today's educational infrastructure has come a long way since a few lectures in a city park, but has it progressed? Plato's most famous student was Aristotle.

Plato returned to Athens and founded the 'Academy' in 387 B.C. Named after a grove of olive trees consecrated by the hero Academus. The Academy developed into a much frequented institution of higher learning. It was, as such, the first university in the western world and continued in existence until 529 A.D. Its curriculum included philosophy and science and followed Plato's conviction that the salvation of the nation lies in the right training of its potential leadership. Plato's followers were called Academici. Cicero called his villa Academia. 

Plato founded the Academy as an institute for the systematic pursuit of philosophical and scientific teaching and research. He presided over it for the rest of his life. The Academy's interests were not limited to philosophy in a narrow sense but also extended to the sciences: there is evidence that Plato encouraged research in such diverse disciplines as mathematics and rhetoric. 

The Academy survived Plato's death. Though its interest in science waned and its philosophical orientation changed, it remained for two and a half centuries a focus of intellectual life. Its creation as a permanent society for the prosecution of both humane and exact sciences has been regarded--with pardonable exaggeration--as the first establishment of a university. 

Much of this information was taken from this website: http://plato.evansville.edu/

For more information, see these links on Plato: 

• Platonica - Amazing website on Plato's philosophy. 
• International Plato Society - Founded as a result of the First Symposium Platonicum, 1986, in Mexico City.