harmonic

adj

1. Pertaining to harmony.
2. Pleasant to hear; harmonious; melodious.

   “harmonic twang of leather, horn, and brass.”

3. Used to characterize various mathematical entities or relationships supposed to bear some resemblance to musical consonance.

   “The harmonic polar line of an inflection point of a cubic curve is the component of the polar conic other than the tangent line.”

4. Recurring periodically.
5. Exhibiting or applying constraints on what vowels (e.g. front/back vowels only) may be found near each other and sometimes in the entire word.
6. Of or relating to a generation an even number of generations distant from a particular person.

   “A person is harmonic with respect to members of his own generation and with respect to members of all even-numbered generations counting away from his own (e.g., his grandparents' generation, his grandchildren's generation, etc.).”

noun

1. A component frequency of the signal of a wave that is an integer multiple of the fundamental frequency.
2. The place where, on a bowed string instrument, a note in the harmonic series of a particular string can be played without the fundamental present.
3. One of a class of functions that enter into the development of the potential of a nearly spherical mass due to its attraction.
4. One's child.

   “Games for the harmonics, (children), YL's and XYL's and the OM's, plus free soda for all.”

   “The harmonics (kids, I mean) sometimes failed to recognize me on the rare occasions when I emerged from the shack […]”