While its common name, "black-chinned hummingbird," is simple enough to not need an etymological (word origin) explanation, the scientific name, Archilochus alexandri, does not share the same fate. Three dictionaries of bird names provide three distinct etymologies. One states that the generic name, Archilochus, honors a 6th century B. C. Thracian poet who was famous for his "savage wit and flaunting of conventions." A second traces the name to the Greek "first among birds" from "arch" meaning "chief'" and "lochos" meaning "body of people."

A third translates Archilochus to "chief brigand" from archos (chief or first in importance) and lochos (ambush or a company of men). The third dictionary ends the definition with a simple question: "But why? Because the bird steals the pollen from the flower and dashes away?" In all three cases, the word alexandri refers to a Dr. Alexandre, who discovered the species in the Sierra Madre of Mexico and sent it to Mexico City. One assumes he has a first name, but none has made its way down through the ages.

The black-chinned hummingbird measures about three and one-half inches long with a three and three-quarter-inch wing span. It weighs three to three and one-half grams, which is about equivalent to the weight of a dime plus a dollar bill. The male is dull metallic green above and gray below. He has a black chin and upper throat with a violet, iridescent lower throat which is known as a gorget (pronounced gore-jet). A white upper breast looks like a collar against the gorget. The female lacks the characteristic coloring on the chin and upper throat and lower throat.