aether: personification of the sky or upper air breathed by the Olympians; son of Erebus and night or of Chaos and darkness
greek deity: a deity worshipped by the ancient Greeks
four-stroke engine: an internal-combustion engine in which an explosive mixture is drawn into the cylinder on the first stroke and is compressed and ignited on the second stroke; work is done on the third stroke and the products of combustion are exhausted on the fourth stroke