Definition of lost cause
- She decided her acting career was a lost cause.
- I'm a lost cause when it comes to anything technical.
- Finishing the project on time seemed like a lost cause.
: not made use of, won, or claimed
: no longer possessed
: no longer known
: a reason for an action or condition : motive
: something that brings about an effect or a result
: a person or thing that is the occasion of an action or state
: to serve as a cause or occasion of
: to compel by command, authority, or force
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