lemon

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A spiny, Asian evergreen tree (Citrus limon) widely cultivated for its yellow, egg-shaped fruit.
2. n. The fruit of this tree, having a yellow aromatic rind and juicy, acid pulp.
3. n. Lemon yellow.
4. n. Informal One that is unsatisfactory or defective: Their new car turned out to be a lemon.
5. adj. Lemon-yellow.
6. adj. Made from lemons.
7. adj. Tasting or smelling like lemons.

Century Dictionary and Cyclopedia

1. n. The fruit of the rutaceous tree Citrus Medica, var. Limonum. It is botanically a berry of an ellipsoid form, knobbed at the apex, with a pale-yellow rind whose outer layer is charged with a fragrant oil, and a light-colored pulp, full of an acid well-flavored juice. The latter, together with lime-juice, is the chief commercial source of citric acid. The oil or essence of lemons is extracted from the rind, at present by the method of expression, which yields the best. It is consumed in large quantities as a flavoring essence and a component of perfumes.
2. n. The tree that yields this fruit. It is found wild in the mountainous regions of India, especially in the north. As a cultivated fruit-tree, it was early known and disseminated by the Arabs, but appears not to have been established in Europe till comparatively late, perhaps brought by the crusaders. It is now cultivated widely in subtropical countries, and is grown industrially in Italy and the adjacent islands, in Spain and Portugal, and in Florida, generally in connection with the orange. The common lemon is a tree from 10 to 15 feet high. Unlike the orange, it is of irregular growth and of sparse foliage. The corolla of its flowers is purplish on the outside, and their fragrance is less heavy than that of orange-flowers. Its closest botanical affinity is with the citron, the two being now considered as varieties of the same species. See Citrus, 2.
3. n. The borhame or sand-sole, a kind of flatfish. See lemon-sole, 1.
4. n. Having lemon as a principal ingredient; impregnated or flavored with lemon: as, lemon candy.
5. n. Of the color of a lemon; lemon-colored: as, lemon silk.

Wiktionary

1. n. A yellowish citrus fruit.
2. n. A semitropical evergreen tree, Citrus limon, that bears such fruits.
3. n. A taste or flavour/flavor of lemons.
4. n. A more or less bright shade of yellow associated with lemon fruits.
5. n. slang A defective or inadequate item.
6. n. Cockney rhyming slang Smart; cheeky, vocal.
7. n. Cockney rhyming slang favour, favor.
8. n. A piece of fanfiction involving explicit sex.
9. adj. Containing or having the flavour/flavor and/or scent of lemons.
10. adj. Of the pale yellow colour/color of lemons.

GNU Webster's 1913

1. n. (Bot.) An oval or roundish fruit resembling the orange, and containing a pulp usually intensely acid. It is produced by a tropical tree of the genus Citrus, the common fruit known in commerce being that of the species Citrus Limonum or Citrus Medica (var. Limonum). There are many varieties of the fruit, some of which are sweet.
2. n. The tree which bears lemons; the lemon tree.
3. n. (Zoöl.) a European species of sole (Solea pegusa).

WordNet 3.0

1. n. a distinctive tart flavor characteristic of lemons
2. n. a small evergreen tree that originated in Asia but is widely cultivated for its fruit
3. n. a strong yellow color
4. n. yellow oval fruit with juicy acidic flesh
5. n. an artifact (especially an automobile) that is defective or unsatisfactory