KEY: Formidable.
SYN: Awful, terrible, alarming, terrifying, discouraging, serious,appalling, fearful, dreadful, horrible, shocking.
ANT: Despicable, weak, contemptible, light, trivial.

• Ire, [See WRATH]
• Iridescent
• Irk
• Ironical, [See IRONY]
• Irony
• Irradiate, [See ILLUMINATE]
• Irrational, [See RATIONAL]
• Irreclaimable, [See RECLAIMABLE]
• Irreconcilable, [See RECONCILABLE]
• Irrecoverable
• Irredeemable, [See REDEEMABLE]
• Irreducible
• Irrefragable, [See REFRAGABLE]
• Irrefutable, [See REFRAGABLE]
• Irregular, [See REGULAR]
• Irrelevant, [See RELEVANT]
• Irreligions
• irreligion, [See RELIGION]
• Irremediable, [See REMEDIABLE]
• Irremissible
• Irremovable
• Irreparable, [See REPARABLE]
• Irreprehensible, [See REPREHENSIBLE]
• Irrepressible
• Irreproachable, [See BLAMELESS]