Is the Tomato a Fruit or a Vegetable?

I've yet again run across the claim that it's an error to call a tomato a "vegetable," because it's really a fruit. I'd blogged about this three and a half years ago, but I thought I'd rerun the post to get reader comments (which weren't enabled when I originally posted this).

The tomato, it seems to me, is both a fruit and a vegetable. It is indeed, botanically speaking, a fruit, a term that's technically defined as "The ripened ovary or ovaries of a seed-bearing plant, together with accessory parts, containing the seeds and occurring in a wide variety of forms." But it's also a vegetable, defined as "[t]he edible part of" "[a] plant cultivated for an edible part, such as the root of the beet, the leaf of spinach, or the flower buds of broccoli or cauliflower." These are from the American Heritage Dictionary, not a scientific work, but my sense is that these are indeed the official definitions.

Now naturally in lay English, the matter is different: Apples aren't usually labeled vegetables, and the categories of vegetable and fruit are usually mutually exclusive. But in lay English, the distinction isn't ripened ovary vs. not a ripened ovary, but rather dessert vs. non-dessert, as the Supreme Court astutely captured in an 1893 import duties case:

Botanically speaking, tomatoes are the fruit of a vine, just as are cucumbers, squashes, beans, and peas. But in the common language of the people, whether sellers or consumers of provisions, all these are vegetables which are grown in kitchen gardens, and which, whether eaten cooked or raw, are, like potatoes, carrots, parsnips, turnips, beets, cauliflower, cabbage, celery, and lettuce, usually served at dinner in, with, or after the soup, fish, or meats which constitute the principal part of the repast, and not, like fruits generally, as dessert.

The attempt to class tomatoes as fruit is not unlike a recent attempt to class beans as seeds, of which Mr. Justice Bradley, speaking for this court, said: "We do not see why they should be classified as seeds, any more than walnuts should be so classified. Both are seeds, in the language of botany or natural history, but not in commerce nor in common parlance. On the other hand in speaking generally of provisions, beans may well be included under the term 'vegetables.' As an article of food on our tables, whether baked or boiled, or forming the basis of soup, they are used as a vegetable, as well when ripe as when green. This is the principal use to which they are put. Beyond the common knowledge which we have on this subject, very little evidence is necessary, or can be produced."