烽火

[ noun ]
a fire (usually on a hill or tower) that can be seen from a distance
<noun.communication>

Beacon \Bea"con\ (b[=e]"k'n), n. [OE. bekene, AS. be['a]cen,
b[=e]cen; akin to OS. b[=o]kan, Fries. baken, beken, sign,
signal, D. baak, OHG. bouhhan, G. bake; of unknown origin.
Cf. {Beckon}.]
1. A signal fire to notify of the approach of an enemy, or to
give any notice, commonly of warning.

No flaming beacons cast their blaze afar. --Gay.

2. A signal, such as that from a lighthouse, or a conspicuous
mark erected on an eminence near the shore, or moored in
shoal water, as a guide to mariners.

3. A high hill near the shore. [Prov. Eng.]

4. That which gives notice of danger.

Modest doubt is called
The beacon of the wise. --Shak.

5. (Navigation) a radio transmitter which emits a
characteristic signal indication its location, so that
vehicles may determine their exact location by locating
the beacon with a radio compass; -- also called {radio
beacon}.

5. [fig.] that which provides guidance or inspiration; the
Constitution has been a beacon for civil rights activists.
[PJC]

{Beacon fire}, a signal fire.