predominant + -ly
predominantly (comparative more predominantly, superlative most predominantly)
- In a predominant manner. Most commonly or frequently by a large margin.
- The membership is predominantly elderly, 90% are over age 60.
- 1992, Rudolf M. Schuster, The Hepaticae and Anthocerotae of North America: East of the Hundredth Meridian, volume V, page 3
- Both groups are predominantly confined to areas with warm to tropical climates […]
This adverb form of the adjective predominant is preferred over predominately (the adverb form of the adjective predominate), which is considered dated or non-standard.