effective, average, marginal. -The effective tax rate is the best measure of the tax burden because it is the average level of tax on all income from taxable and nontaxable sources. -The average tax rate measures the average level of tax on only taxable income.
Navigating the eschaton. The eschaton is something to be avoided and something to be courted. It is a virtual singularity of human consciousness marking the end of the historical epoch. In itself it is a neutral event, one to be reckoned with. It is a point of leverage for wielding the human spirit.
Triton. Triton is the only large satellite in the solar system to circle a planet in a retrograde direction -- in a direction opposite to the rotation of the planet. It also has a density of about 2.066 grams per cubic centimeter (the density of water is 1.0 gram per cubic centimeter).