"lacking" in the verb sense
1. miss, lack
be without
"This soup lacks salt"
"There is something missing in my jewelry box!"
"lacking" in the adjective sense
1. deficient, lacking, wanting
inadequate in amount or degree
"a deficient education"
"deficient in common sense"
"lacking in stamina"
"tested and found wanting"
2. lacking, absent, missing, wanting
nonexistent
"the thumb is absent"
"her appetite was lacking"
Source: WordNet® (An amazing lexical database of English)
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