Unitedness is from united (past participle of unite, from Late Latin unire 'to join into one', from Latin unus 'one') + -ness. Important recorded forms include unire (Latin), unus (Latin), and *óynos (Proto-Indo-European). Morphologically, the native -ness suffix turns an adjective or quality word into an abstract noun naming the state or condition. The modern sense is largely compositional, with the historical elements narrowing into a stable English lexical item. In current use it covers the state of being joined together in agreement. The wider family includes related words such as unite, united, and unity.