To make small adjustments to something in order to achieve the best or a desired performance. The engineer had to fine-tune the engine to improve its efficiency.
To improve or perfect by making minor changes. The musician spent hours fine-tuning the composition before the concert.
To adapt a pre-trained machine-learning model to a specific task or dataset by continuing its training with additional, task-specific data. The data scientists fine-tuned the language model on medical records to improve diagnostic accuracy.