D defs.my
Entry 1 sense Webster, 1913

Aclinic

/(ȧ*klĭn"ĭk)/ · A·clin·ic · IPA
01 a. Without inclination or dipping; -- said of the imaginary line near the earth's equator on which the magnetic needle balances itself horizon…
  1. 1.
    Without inclination or dipping; -- said of the imaginary line near the earth's equator on which the magnetic needle balances itself horizontally, having no dip. The aclinic line is also termed the magnetic equator.(Physics.)