- 3.235.172.213

Mean, a.

1. Occupying a middle position; middle; being about midway between extremes.

*Being of middle age and a mean stature.* --*Sir. P. Sidney.*

2. Intermediate in excellence of any kind.

*According to the fittest style of lofty, mean, or lowly.* --*Milton.*

3. Math. Average; having an intermediate value between two extremes, or between the several successive values of a variable quantity during one cycle of variation; as, mean distance; mean motion; mean solar day.

**Mean distance** (of a planet from the sun) Astron., the average of the distances throughout one revolution of the planet, equivalent to the semi-major axis of the orbit.

**Mean error** Math. Phys., the average error of a number of observations found by taking the mean value of the positive and negative errors without regard to sign.

**Mean-square error**, *or* **Error of the mean square** Math. Phys., the error the square of which is the mean of the squares of all the errors; -- called also, mean square deviation, mean error.

**Mean line**. Crystallog. Same as Bisectrix.

**Mean noon**, noon as determined by mean time.

**Mean proportional** (between two numbers) Math., the square root of their product.

**Mean sun**, a fictitious sun supposed to move uniformly in the equator so as to be on the meridian each day at mean noon.

**Mean time**, time as measured by an equable motion, as of a perfect clock, or as reckoned on the supposition that all the days of the year are of a mean or uniform length, in contradistinction from __apparent__ time, or that actually indicated by the sun, and from __sidereal__ time, or that measured by the stars.