Spices are seasonings for food that come from the bark, buds, fruit or flower parts, roots, seeds or stems of various aromatic plants and trees.

Harder - According to the American Spice Trade Association (ASTA), spices are 'any dried plant product used primarily for seasoning purposes.' This definition covers a wide range of plant and plant parts: tropical aromatics, leafy herbs, spice seeds, roots, dehydrated vegetables, and spice blends.

At one time only tropical aromatics like pepper, cinnamon, and cloves were considered a spice. The leaves and seeds of temperate-zone plants like basil and oregano were known as herbs. Today this classification has shifted somewhat, even though still used in some circles. The term spice now generally includes a whole range of elements: spices, herbs, blends and dehydrated vegetables.

Legally the Food and Drug Administration (FDA) still considers dehydrated vegetables as separate and distinct from spices; they require such seasonings to be labeled differently than spices. Spices used for coloring like paprika and saffron are also labeled separately or as a 'spice coloring.' The U.S. Department of Agriculture (USDA) follows similar rules as the FDA. Spice colorings and mustard must be labeled separate from spices, onion and garlic are listed as flavors, and all other dehydrated vegetables are labeled separately by name.