Coleoptera is an order of insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s commonly called beetles. The word "coleoptera" is from the Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

 , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 than any other order, constituting almost 25% of all known life-forms. About 40% of all described insect species are beetles (about 400,000 species), and new species are discovered frequently.