An Etymological Dictionary of Astronomy and Astrophysics

1. The top, summit, or apex.
   

   2. To tilt or cause to tilt; overturn, upset, or overthrow.

Etymology (EN): 1) M.E. tip, from M.L.G. or M.Du. tip “utmost point, extremity” (cf. Ger. zipfel, a diminutive formation).

2. From, tip noun from tip (v.) “to overturn, upset,” from M.E. typen “to upset, overturn.”

Etymology (PE): 1) Nok “tip,” variant tok.