Impermanent (9)
'impermanent' is the definition.
(similar in meaning)
This is the entire clue.
(Other definitions for transient that I've seen before include "Passing, short-lived" , "Lasting little time" , "fugitive" , "Here today, gone tomorrow" , "Lasting a short time" .)
'impermanent' is the definition.
(I know that impermanent can be written as temporary)
This is all the clue.
(Other definitions for temporary that I've seen before include "short-term" , "For a short period only" , "Not permanent or lasting" , "Not for long" , "Impermanent" .)
(Another definition for adhoc that I've seen is " for this special purpose".)