The phrase "great pioneers" refers to people who are highly regarded for being the first to explore or achieve something important or groundbreaking. They are considered leaders and innovators in their respective fields. Full definition
In the Classroom: According to Rachel Dickinson's Great Pioneer Projects You Can Build Yourself, pioneers walked about 15 miles a day for five months. (booklistonline.com)
In addition to a selection of Chillida's works, this gallery contains pieces by great pioneers like Fontana, Oteiza, and Naum Gabo and other artists whose work followed in the wake of their investigations, including Agostino Bonalumi, Sue Fuller, and Norbert Kricke. (artsy.net)