Limitless (12)
'limitless' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for immeasurable that I've seen before include "Limitless" , "very big" , "Fathomless" , "Too large to quantify" , "Vast mass" .)
'limitless' is the definition.
(similar in meaning)
This is the entire clue.
(Other definitions for infinite that I've seen before include "Boundless" , "Without limit" , "Having no limits in time, space etc." , "Unbounded" , "Without boundaries" .)