Meaning

noun the fifth and highest element after air and earth and fire and water; was believed to be the substance composing all heavenly bodies

noun the purest and most concentrated essence of something

noun the most typical example or representative of a type

originPIE word *pénkʷe From Middle English, borrowed from Middle French, from Medieval Latin quinta essentia (“fifth essence, aether”), equivalent to quint- + essence. "Essence" in this context is a synonym for "element". In pre-atomic/Aristotelian theory, there are four known elements or essences — Earth, Air, Fire and Water — and a putative fifth element (aether), which is considered to be of…

Etymology from Wiktionary, CC BY-SA 3.0