fine-tune in WordNet English dictionary

1. make fine adjustments or divide into marked intervals for optimal measuring
   "calibrate an instrument"; "graduate a cylinder"
   calibrate  graduate  fine-tune 
   
2. improve or perfect by pruning or polishing
   "refine one's style of writing"
   polish  refine  fine-tune  down 
   
3. adjust finely
   "fine-tune the engine"
   fine-tune  tweak 
   

fine-tune in English Wiktionary