1. Not open to challenge
   "unchallengeable facts"; "a position of unchallengeable supremacy"

See also: noncontroversial, uncontroversial

• system command
• system error
• system of logic
• system of macrophages
• system of measurement
• system of numeration
• system of rules
• system of weights
• system of weights and measures
• system program
• systema alimentarium
• systema digestorium
• systema lymphaticum
• systema nervosum
• systema nervosum centrale
• systema nervosum periphericum
• systema respiratorium
• systema skeletale
• systema urogenitale
• systematic
• systematic desensitisation
• systematic desensitization
• systematical
• systematically
• systematics