From The Collaborative International Dictionary of English v.0.48 :
fine-tune \fine-tune\ v. t.
to adjust carefully and precisely so as to achieve optimum
performance or efficiency; as, The mechanic fine-tuned the
engine.
[WordNet 1.5]
From WordNet (r) 3.0 (2006) :
fine-tune
v 1: improve or perfect by pruning or polishing; "refine one's
style of writing" [syn: polish, refine, fine-tune,
down]
2: adjust finely; "fine-tune the engine" [syn: fine-tune,
tweak]
3: make fine adjustments or divide into marked intervals for
optimal measuring; "calibrate an instrument"; "graduate a
cylinder" [syn: calibrate, graduate, fine-tune]