signalnoun
The radar picked up a distress signal from a non-military aircraft within ten miles of the base.
A beacon on the stricken ship began to issue a distress signal that was picked up by a satellite.
The wireless operator tapped out a distress signal.

SMART Vocabulary: related words and phrases

Signs, signals and symbols
acid test
backward slash
backwards slash
beacon
breadcrumb
hieroglyphically
iconographic
iconographically
iconography
lagging indicator
obelus
octothorpe
paraph
penalty flag
pilcrow
pointer
prompt
the all-clear
token
torch