had been pioneering
Past perfect progressive conjugation of pioneer. There are other translations for this conjugation.

pioneer

Popularity
500+ learners.
Though smaller groups had been pioneering these sentiments for many years prior, it is encouraging to see more people taking up this work.
Aunque los grupos más pequeños habían sido pioneros en estos sentimientos durante muchos años anteriores, es alentador ver a más personas emprender este trabajo.
Other Dictionaries
Explore the meaning of pioneer in our family of products.
Word of the Day
frost