/ ˈlaɪfləs; NAmE / adjective
1.
( formal ) dead or appearing to be dead
SYN inanimate
2.
not living; not having living things growing on or in it :
lifeless machines
a lifeless planet
3.
dull; lacking the qualities that make sth/sb interesting and full of life
SYN lacklustre :
his lifeless performance on stage
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WORD ORIGIN
Old English līflēas (see life , -less ).