n.
Pronunciation: ˌ p ī - ə - ' nir
Function: noun
Etymology: Middle French pionier, from Old French peonier foot soldier, from peon foot soldier, from Medieval Latin pedon-, pedo ― more at PAWN
Date: 1523
1 : a member of a military unit usually of construction engineers
2 a : a person or group that originates or helps open up a new line of thought or activity or a new method or technical development b : one of the first to settle in a territory
3 : a plant or animal capable of establishing itself in a bare, barren, or open area and initiating an ecological cycle