Describing birds that have a particular arrangement of palatal bones in the skull, characteristic of certain songbird groups.
From Greek aigithalos (bird) plus gnathos (jaw), with the adjectival suffix -ous. Created as a technical ornithological term in 19th-century taxonomic classifications.
If you could x-ray a bird's skull, you'd see some have palatal bones arranged like a fancy puzzle. Aegithognathous birds have one specific arrangement, though modern DNA testing has shown this skull pattern isn't a reliable family tree marker.
Complete word intelligence in one call. Free tier — 50 lookups/day.