(1) Deprived of life; no longer living
"A lifeless body"
(2) Not having the capacity to support life
"A lifeless planet"
(3) Lacking animation or excitement or activity
"The party being dead we left early"
"It was a lifeless party until she arrived"
(4) Destitute or having been emptied of life or living beings
"After the dance the littered and lifeless ballroom echoed hollowly"