An Etymological Dictionary of Astronomy and Astrophysics

1. An inclined surface; deviation from the horizontal or vertical.
   

2. The tangent of the angle formed by the intersection of a given straight line and the X-axis
   of a system of Cartesian coordinates.
   

3. The derivative of the function whose graph is a given curve evaluated at a designated point.
   

4. The exponent of the → initial mass function .
   See also → Salpeter slope.
   

5. → slope parameter.

Etymology (EN): From M.E. aslope (adv.) “on the incline,” from O.E. *aslopen, p.p. of aslupan “to slip away,” from a- “away” + slupan “to slip.”

Etymology (PE): Šib “slope, descent, declivity,” contraction of nešib, našib “declivity, descent; lowness of ground, slope of any place;” Mid.Pers. nišēp “declivity, (astrology) dejection,” Av. *nixšvaēpā-, xšvaēpā- “bottom, rear.”