acorn squash

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A type of winter squash shaped somewhat like an acorn and having longitudinal ridges, a variously colored rind, and yellow to orange flesh.

Wiktionary

1. n. Any of several varieties of a plant, Cucurbita pepo, being a dark green winter squash having yellow to orange flesh.

WordNet 3.0

1. n. small dark green or yellow ribbed squash with yellow to orange flesh
2. n. squash plant bearing small acorn-shaped fruits having yellow flesh and dark green or yellow rind with longitudinal ridges