noun

1. Archaic a member of a military engineer unit trained to construct or demolish bridges, roads, trenches, etc.
2. ☆ a person who goes before, preparing the way for others, as an early settler or a scientist doing exploratory work
3. a plant, animal, etc. that starts a new cycle of life in a barren area

Etymology: Fr pionnier < OFr peonier, foot soldier < peon: see peon

adjective

1. being one of the first of its kind
2. of or characteristic of the settlers of a new territory

intransitive verb

transitive verb

1. to prepare or open (a way, etc.)
2. ☆ to be a pioneer in or of