Halfhearted (adjective)

1. Lacking enthusiasm or commitment; not wholehearted.
2. Not showing much interest or energy.

Origin:

From half + hearted, first attested in the early 17th century.

Examples:

1. He made a halfhearted attempt to fix the problem.
2. She had a halfhearted attitude towards her job.
3. His apology was halfhearted at best.
4. The team gave a halfhearted performance.
5. She had a halfhearted smile on her face.