This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. A knob-shaped handle for opening and closing a door.

n. A circular device attached to a door, the rotation of which permits the unlatching of the door.

n. a knob used to release the catch when opening a door (often called `doorhandle' in Great Britain)

"It's simple for a thief to break glass panels and then reach in and open a doorknob from the inside."

knob   

padlock    keyhole    knocker    knob    ashtray    latch    door-knob    hasp    paperweight    deadbolt