In Daoist cosmology,
天仙 are the highest rank of immortals — beings who have ascended to the celestial realms, above
地仙 (earth-immortals) and
人仙 (human-immortals). In modern usage the figurative 'stunningly beautiful woman' sense dominates:
美若天仙 ('as beautiful as a celestial fairy') is a stock phrase used in fiction and online compliments.
