lack ‧ ing /ˈlækɪŋ/ BrE AmE adjective [not before noun]
1 . not having enough of something or any of it
lacking in
He was lacking in confidence.
She seems to be entirely lacking in intelligence.
The new designs have all been found lacking in some important way.
2 . if something that you need or want is lacking, it does not exist:
Financial backing for the project is still lacking.
These qualities are sadly lacking today.