What does "barren" mean?

Additional senses

1. 2.Unproductive; fruitless; unprofitable; empty. Brilliant but barren reveries. Prescott. Some schemes will appear barren of hints and matter. Swift.
2. 3.Mentally dull; stupid. Shak. Barren flower, a flower which has only stamens without a pistil, or which as neither stamens nor pistils. -- Barren Grounds (Geog.), a vast tract in British America northward of the forest regions. -- Barren Ground bear (Zoöl.), a peculiar bear, inhabiting the Barren Grounds, now believed to be a variety of the brown bear of Europe. -- Barren Ground caribou (Zoöl.), a small reindeer (Rangifer Groenlandicus) peculiar to the Barren Grounds and Greenland.
3. 4.A tract of barren land.
4. 5.pl. Elevated lands or plains on which grow small trees, but not timber; as, pine barrens; oak barrens. They are not necessarily sterile, and are often fertile. [Amer.] J. Pickering.