Short answers, pulled from the story.
Apotheosis is the glorification of a subject to divine levels, treating a human being, another living thing, or an abstract idea as a deity. The word is also used figuratively for the deification, glorification, or exaltation of a principle or practice.
Julius Caesar was the first Roman dictator posthumously deified, in 42 BC, by his adopted son, the triumvir Octavian. Before Caesar, only the god Quirinus, through his identification with Romulus, had been recognized as having undergone apotheosis in Rome.
The Roman ceremony was called a consecratio, and it included releasing an eagle believed to carry the deceased ruler's soul up to heaven. It usually followed a Senate vote confirming the emperor's divinity and is depicted in art such as the relief on the Column of Antoninus Pius.
The Apotheosis of Washington, painted in 1865, is located high in the dome of the United States Capitol Building. It shows a founding American figure risen into divine company, in the tradition of classical apotheosis art.
Mormon denominations describe apotheosis using the term exaltation. The Church of Jesus Christ of Latter-day Saints teaches that sufficiently obedient members reach the celestial kingdom's highest level, live eternally with God, and become gods who create worlds.
François Couperin, Hector Berlioz, Igor Stravinsky, Maurice Ravel, Karel Husa, and Aram Khachaturian all used apotheosis, or the French Apotheose, as a title or section name in their works. Franz Liszt's symphonic works are also closely associated with apotheosis-style finales.