Neb
One possible three-letter word for "bill" would be "IOU." Another might be "neb," which is a bird's bill.
I would assume that the whippoorwill's bill is the same as other birds'... a NIB.
Another name for a owl's beak is called a bill or rostrum.
NIB
Dun
neb
yes all birds have a beak or a bill
The serial number and most times the letter on the bill.
Marshy birds
Bill is made up of keratin protein .
yes all birds have a beak or a bill
If you mean the letter inside the round seal, it's an indicator of which of the 12 Federal Reserve districts issued the bill. If you're referring to another letter, please post a more specific question.