The phrase "defined set" refers to a specific and clear group or collection of things. It means that there is a clear and precise description or definition of the items included in the set. Full definition
Conventional transmissions (both manual and automatic) consists of defined set of gear ratios or speeds. (rediff.com)
Each game has a clearly defined set of rules that are never broken, allowing players to properly analyze the problems they are faced with. (thezombiechimp.com)
Apply paragraph formatting to your document by defining a set formatting rules that get applied to all paragraphs. (feedspot.com)