slang an engineer's small screwdriver, used for fine adjustments
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Examples from the Web for tweaker
Historical Examples of tweaker
I did wonder,' he said, 'whether you were such an innocent as really to believe it was a tweaker.'Life of Frederick Courtenay Selous, D.S.O.
McTurk read the papers of those years and could be trusted for general information, which he used as he used his "tweaker."Stalky & Co.