type genus of the Aceraceae; trees or shrubs having winged fruit
"The maple tree, belonging to the acer genus, produces distinctive winged seeds known as samaras."
Obsolete spelling of acre
"The old manuscript listed an acer in the field where he once farmed."
The word comes from the Latin genus name Acer, which refers to the maple tree family. It entered English through scientific classification rather than evolving directly from an older common term.