Celestial shapes lost nonelastic forms (14)
I believe the answer is:
constellations
'celestial shapes' is the definition.
The answer and definition can be both related to thinking as well as being plural nouns.
Perhaps they are linked in a way I don't understand?
'lost nonelastic forms' is the wordplay.
'forms' is an anagram indicator.
'lost'+'nonelastic'='lostnonelastic'
'lostnonelastic' is an anagram of 'CONSTELLATIONS'.
Can you help me to learn more?
(Another definition for constellations that I've seen is " Groups of stars".)