Definition of sheathbill
: either of two white shorebirds (Chionis alba and C. minor of the family Chionididae) of colder parts of the southern hemisphere that have a horny sheath over the base of the upper mandible and suggest the pigeons in general appearance
First Known Use of sheathbill
Learn More about sheathbill
Britannica.com: Encyclopedia article about sheathbill
Seen and Heard
What made you want to look up sheathbill? Please tell us where you read or heard it (including the quote, if possible).