Characteristic of, befitting, or relating to a duke; having the qualities or appearance associated with ducal rank and nobility.
From 'duke' plus the adjective-forming suffix '-ly.' Similar constructions include 'kingly,' 'queenly,' and 'lordly,' all meaning worthy of or befitting that rank.
Medieval writers used '-ly' adjectives to describe nobility—something 'dukely' meant it had the proper dignity, which was all about maintaining strict social hierarchies.
Complete word intelligence in one call. Free tier — 50 lookups/day.