prickly pear

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various opuntias having bristly, flattened stem segments, often colorful flowers, and ovoid prickly fruit.
• noun The edible fruit of certain of these cactuses.

from The Century Dictionary.

• noun The fruit of cacti of the genus Opuntia, a pear-shaped or ovoid berry, in many cases juicy and edible, armed with prickles or nearly smooth.
• noun Any plant of this genus, primarily O. vulgaris (or O. Rafinesquii, which is not always distinguished from it). See Opuntia.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of various spiny cacti of the genus Opuntia, or the fruit, often edible, of such a plant.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun cacti having spiny flat joints and oval fruit that is edible in some species; often used as food for stock
• noun round or pear-shaped spiny fruit of any of various prickly pear cacti