English Informal and Formal Words List; Informal Formal Ask for Request Look into Investigate Refer to Consult Hungry Famished But However Wrong Incorrect Mad Insane Let Allow Eager Avid Dare Challenge Hurt Damage Show Demonstrate Avoid Evade Sick ill Give up Quit Empty Vacant Mend Repair Idea Notion See Observe Need Require Informal Formal Live Reside Whole Entire Blow up Explode Thanks Gratitude Worse Inferior Keep Preserve Dim Indistinct Death Demise Job Occupation Dad Father Hopeless Futile Call on Visit Whole Complete Free Liberate Get Obtain Let Permit Anyway Nevertheless I think In my opinion All right Acceptable Put up