MISSING

verb

1. To fail to hit.
2. To fail to achieve or attain.
3. To avoid; to escape.

noun

1. A value that is missing.

adjective

1. Not able to be located; gone, misplaced.
2. Not present when it (they) should be.
3. Of an internal combustion engine: running roughly due to an occasional lack of a spark or other irregular fault.