sunflower

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of several plants of the genus Helianthus, especially H. annuus, having tall coarse stems and large, yellow-rayed flower heads that produce edible seeds rich in oil.
2. n. The seedlike fruit or the seeds of this plant.
3. n. A brilliant yellow to strong or vivid orange yellow.

Century Dictionary and Cyclopedia

1. n. A plant of the genus Helianthus, so named from its showy golden radiate heads. The common or annual sunflower is H. annuus, a native of the western United States, much planted elsewhere for ornament, and for its oily seeds, which are valued as food for poultry and as a remedy for heaves in horses. (See also sunflower-oil, below.) It is naturally robust; but in cultivation it grows to a height of 10 or 12 feet; the disk of the head broadens from an inch or so to several inches, the leaves becoming more heart-shaped and often over a foot long. A favorite profusely flowering garden sunflower known as H. multiflorus is referred for origin to the same species. Other cultivated species are H. orgyalis of the great plains of Nebraska, etc., a smooth plant 10 feet high, with narrow graceful leaves, and H. argophyllus of Texas, with soft silky white foliage. H. tuberosus is the Jerusalem artichoke (which see, under artichoke). Bee Helianthus, and cut under authoclinium.
2. n. The rock-rose or sun-rose. See Helianthemum.
3. n. The marigold, Calendula officinalis, from its opening and closing with the ascent and descent of the sun.
4. n. In civil engineering, a full-circle protractor arranged for vertical mounting on a tripod. It has two levels arranged at right angles with one another, adjusting devices, and an adjustable arm pivoted to the center of the protractor; the tripod mounting is effected by means of an open-ended tube to which the protractor is attached, the tube being passed vertically through the ball of the ball-and-socket joint of the tripod, and held therein by a set-screw. The instrument is used in measuring sectional areas of tunnels.
5. n. In writing-telegraphs and other electrical instruments and apparatus, a series of alternate conducting and insulating segmental pieces or tablets symmetrically arranged in circular form, each conducting piece being connected with a source of electricity and also with the ground. It is operated by a tracer (also having a ground connection) rotated over the series, and making a circuit in passing over any of the conducting segments and breaking it when passing over any of the insulating segments.

Wiktionary

1. n. Any plant of the genus Helianthus, so called probably from the form and color of its floral head, having the form of large disk surrounded by yellow ray flowers; the commonly cultivated sunflower is Helianthus annuus, a native of America.
2. n. colour a bright yellow, like that of the flower petals.

GNU Webster's 1913

1. n. Any plant of the genus Helianthus; -- so called probably from the form and color of its flower, which is large disk with yellow rays. The commonly cultivated sunflower is Helianthus annuus, a native of America.

WordNet 3.0

1. n. any plant of the genus Helianthus having large flower heads with dark disk florets and showy yellow rays