sloe

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. See blackthorn.
2. n. Either of two eastern North American plum trees or shrubs, Prunus alleghaniensis, having dark purple fruit, or P. americana, having yellow or red fruit.
3. n. The tart plumlike fruit of either of these plants.

Century Dictionary and Cyclopedia

1. n. The fruit of the blackthorn, Prunus spinosa, a small bluish-black drupe; also, the fruit of P. umbellata.
2. n. The blackthorn, Prunus spinosa, a shrub of hedgerows, thickets, etc., found in Europe and Russian and central Asia. It is of a rigid much-branching spiny habit, puts forth profuse pure-white blossoms before the leaves, and produces a drupe also called a Sloe. (See def. l.) The wood is hard and takes a fine polish, and is nsed for walking-sticks, tool-handles, etc. The wild fruit is aus-tere and of little value; but it is thought to be the original of the common cultivated plum, P. domestica. (See plum, 2.) The sloe, or black sloe, of the southern United States is P. umbellata, a small tree with a pleasant red or black fruit, which is used as a preserve.

Wiktionary

1. n. The small, bitter, wild fruit of the blackthorn (Prunus spinosa); also, the tree itself.
2. n. Any of various other plants of the genus Prunus, as a shrub or small tree, Prunus alleghaniensis, bearing dark-purple fruit.

GNU Webster's 1913

1. n. (Bot.) A small, bitter, wild European plum, the fruit of the blackthorn (Prunus spinosa); also, the tree itself.

WordNet 3.0

1. n. a thorny Eurasian bush with plumlike fruits
2. n. wild plum of northeastern United States having dark purple fruits with yellow flesh
3. n. small sour dark purple fruit of especially the Allegheny plum bush