secretion

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The process of secreting a substance, especially one that is not a waste, from the blood or cells: secretion of hormones; secretion of milk by the mammary glands.
2. n. A substance, such as saliva, mucus, tears, bile, or a hormone, that is secreted.
3. n. The act of concealing something in a hiding place.
4. n. The act of stealing something secretly.

Century Dictionary and Cyclopedia

1. n. In physiology:
2. n. In animal physiology, the process of preparing and separating substances by glandular activity. The product or secretion usually consists of substances previously existing in the blood, such as water, salts, etc., combined with others which have been elaborated by the glandular epithelium from more or less different substances in the blood. The secretion may be eliminated from the body as detrimental, as urine, or it may be used, as the digestive secretions, to serve requirements of the organism or (as the milk) those of its offspring. Secretions which are merely eliminated as detrimental are called excretions. The act of secreting seems, in most instances at least, to be a vital act of the glandular epithelium, and is often, if not always, under direct nervous control.
3. n. In vegetable physiology, the process by which substances are separated from the sap of vegetables. The descending sap of plants is not merely subservient to nutrition, but furnishes various matters which are secreted or separated from its mass, and afterward elaborated by particular organs. These secretions are exceedingly numerous, and constitute the great bulk of the solid parts of plants. They have been divided into— general or nutritious secretions, the component parts of which are gum, sugar, starch, lignin, albumen, and gluten; and special or non-assimilable secretions, which may be arranged under the heads of acids, alkalis, neuter principles, resinous principles, coloring matters, milks, oils, resins, etc.
4. n. A substance or product secreted, or elaborated and emitted.
5. n. Synonyms Excretion, Secretion. See excretion.
6. n. A mineral deposit formed in a fissure or cavity by growth inward from the walls: contrasted with concretion, which grows outward from a nucleus.

Wiktionary

1. n. Any substance that is secreted by an organism.
2. n. The act of secreting a substance, especially from a gland.
3. n. The act of hiding something.

GNU Webster's 1913

1. n. The act of secreting or concealing.
2. n. (Physiol.) The act of secreting; the process by which material is separated from the blood through the agency of the cells of the various glands and elaborated by the cells into new substances so as to form the various secretions, as the saliva, bile, and other digestive fluids. The process varies in the different glands, and hence are formed the various secretions.
3. n. (Physiol.) Any substance or fluid secreted, or elaborated and emitted, as the gastric juice.

WordNet 3.0

1. n. the organic process of synthesizing and releasing some substance
2. n. a functionally specialized substance (especially one that is not a waste) released from a gland or cell