d]
| 1. | a group of three, esp. of three closely related persons or things. |
| 2. | Chemistry.
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| 3. | Music. a chord of three tones, esp. one consisting of a given tone with its major or minor third and its perfect, augmented, or diminished fifth. |
| 4. | (initial capital letter ) Military. the three categories of strategic-nuclear-weapons delivery systems: bombers, land-based missiles, and missile-firing submarines. |
triad tri·ad (trī'ād', -əd)
n.
A collection of three things or symptoms having something in common.
The transverse tubule, and the terminal cisternae on each side of it, in a skeletal muscle fiber.
triad
in chemistry, any of several sets of three chemically similar elements, the atomic weight of one of which is approximately equal to the mean of the atomic weights of the other two. Such triads-including chlorine-bromine-iodine, calcium-strontium-barium, and sulfur-selenium-tellurium-were noted by the German chemist J.W. Dobereiner between 1817 and 1829. The triad was the earliest atomic-weight classification of the elements
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