等角线
恒向线
无变形线
斜航

[ noun ]
a line on a sphere that cuts all meridians at the same angle; the path taken by a ship or plane that maintains a constant compass direction
<noun.location>

Rhumb \Rhumb\, n. [F. rumb, Sp. rumbo, or Pg. rumbo, rumo,
probably fr. Gr. ??? a magic wheel, a whirling motion, hence
applied to a point of the compass. See {Rhomb}.] (Navigation)
A line which crosses successive meridians at a constant
angle; -- called also {rhumb line}, and {loxodromic curve}.
See {Loxodromic}.

{To sail on a rhumb}, to sail continuously on one course,
following a rhumb line.