前沿
前缘

Leading edge \Lead"ing edge\n.
1. (Aeronautics) the front edge of an airfoil; same as
{{Advancing edge}}, above.
[Webster 1913 Suppl.]

2. the front edge of anything that moves; also used
metaphorically, as the leading edge in art. See also
{cutting edge}.
[PJC]


Advancing edge \Ad*van"cing edge\ (A["e]ronautics)
The front edge (in direction of motion) of a supporting
surface; -- contr. with {following edge}, which is the rear
edge.
[Webster 1913 Suppl.]