Bird names aren't always as simple as "chickadee," that bird at your feeder.
Officially, it's the black-capped chickadee, one of seven chickadee species in North America. The others are Carolina, mountain, gray-headed, boreal, Mexican and chestnut-backed.
All birds have Latin as well as common names, a scientific name used worldwide regardless of local designation. This enables clear understanding of which particular bird you're talking about, regardless of language. These names are used almost exclusively in scholarly publications, and also can be found in your ID guides, in italics just below the common name.
The Latin name for our chickadee is Poecile atricapillus. That's the name researchers would use here or in France or Cuba or China.
Poecile comes from the Greek poikil, meaning spotted, dappled, pied, many-colored. Atricapillus is Latin. Atri- means black or dark. Capillus means cap. Hence black-capped chickadee.
Scientific names come from a system created by a Swedish scientist, Carl von Linné (1707-1778). He is better and most appropriately known by the Latin form of his name, Linnaeus.
He was a botanist, physician and zoologist who described a formal system for naming organisms. With some modification, his original system is used today worldwide.
The system has eight classifications, each dividing into ever smaller parts. This is how it works for the chickadee: