To be without, to need, to require.
My life lacks excitement.
To be short (of or for something).
He'll never lack for company while he's got all that money.
To be in want.
To see the deficiency in (someone or something); to find fault with, to malign, reproach.
The absence of something; a lack.
Missing or not having enough of (a good quality, etc).
This cheese is lacking in pungency.
Not carrying a firearm.
Are you packing or lacking?