Inanimate (4)
'inanimate' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for lifeless that I've seen before include "late?" , "Without vigour" , "Inanimate or dead" , "Dull" , "Passive" .)
'inanimate' is the definition.
(synonyms)
This is all the clue.
(Other definitions for dead that I've seen before include "Lifeless" , "dull" , "Passed on" , "Unresponsive" , "Not functioning; numb" .)