A registry cleaner is a type of software utility designed for the Microsoft Windows operating system whose purpose is to remove redundant or unwanted items from the Windows registry.
A person used or exploited by another
A thing used in an occupation or pursuit
(tool) an implement used in the practice of a vocation
(tool) instrument: the means whereby some act is accomplished; "my greed was the instrument of my destruction"; "science has given us new tools to fight disease"
A device or implement, esp. one held in the hand, used to carry out a particular function
(tool) drive; "The convertible tooled down the street"