Antonyms for Certain

Antonyms starting with letter I

• indefinite

  fixed, referring to a specifically known amount, undoubtable
• indistinct

  undoubtable
• imprecise

  referring to a specifically known amount
• indeterminate
• invalid

  undoubtable
• inexact

  referring to a specifically known amount
• iffy
• incertain
• indecisive
• inconstant
• improbable
• inconclusive