Red

How curious to see the ways in which dictionaries attempt to define the word red. Here are just a few.

Merriam-Webster's Medical Dictionary -
Main Entry: 2red
Function: noun
1 : a color whose hue resembles that of blood or of the ruby or is that of the long-wave extreme of the visible spectrum
2 : a pigment or dye that colors red —see CONGO RED, NEUTRAL RED, VITAL RED

Kernerman English Multilingual Dictionary (Beta Version) -
red1 [red] noun, adjective
(of) the colour of blood
Example: a red car/dress / cheeks; Her eyes were red with crying.

And check out green:

Dictionary.com Unabridged (v 1.1) -
green [green] Pronunciation Key - Show IPA Pronunciation adjective, -er, -est, noun, verb
–adjective
1. of the color of growing foliage, between yellow and blue in the spectrum: green leaves.
2. covered with herbage or foliage; verdant: green fields.
3. characterized by the presence of verdure.
4. made of green vegetables, as lettuce, spinach, endive, or chicory: a green salad.
5. not fully developed or perfected in growth or condition; unripe; not properly aged: This peach is still green.
6. unseasoned; not dried or cured: green lumber.
7. immature in age or judgment; untrained; inexperienced: a green worker.
8. simple; unsophisticated; gullible; easily fooled.
9. fresh, recent, or new: an insult still green in his mind.
10. having a sickly appearance; pale; wan: green with fear; green with envy.
11. full of life and vigor; young: a man ripe in years but green in heart.
12. environmentally sound or beneficial: green computers.
13. (of wine) having a flavor that is raw, harsh, and acid, due esp. to a lack of maturity.
14. freshly slaughtered or still raw: green meat.
15. not fired, as bricks or pottery.
16. (of cement or mortar) freshly set and not completely hardened.
17. Foundry.
a. (of sand) sufficiently moist to form a compact lining for a mold without further treatment.
b. (of a casting) as it comes from the mold.
c. (of a powder, in powder metallurgy) unsintered.
–noun
18. a color intermediate in the spectrum between yellow and blue, an effect of light with a wavelength between 500 and 570 nm; found in nature as the color of most grasses and leaves while growing, of some fruits while ripening, and of the sea.
19. Art. a secondary color that has been formed by the mixture of blue and yellow pigments.
20. green coloring matter, as paint or dye.
21. green material or clothing: to be dressed in green.
22. greens,
a. fresh leaves or branches of trees, shrubs, etc., used for decoration; wreaths.
b. the leaves and stems of plants, as spinach, lettuce, or cabbage, used for food.
c. a blue-green uniform of the U.S. Army.
23. grassy land; a plot of grassy ground.
24. a piece of grassy ground constituting a town or village common.
25. Also called putting green. Golf. the area of closely cropped grass surrounding each hole.
26. bowling green.
27. a shooting range for archery.
28. Informal. green light (def. 1).
29. Slang. money; greenbacks (usually prec. by the): I'd like to buy a new car but I don't have the green.
30. (initial capital letter) a member of the Green party (in Germany).
–verb (used without object), verb (used with object)
31. to become or make green.
32. Informal. to restore the vitality of: Younger executives are greening corporate managements.
—Idiom
33. read the green, to inspect a golf green, analyzing its slope and surface, so as to determine the difficulties to be encountered when putting.
[Origin: bef. 900; ME, OE gréne; c. G grün; akin to grow]