signal

/ˈsɪɡnəl/
noun
  1. A sign, gesture, or sound that gives information or instructions.
    • She gave a thumbs-up signal to show that everything was okay.
    • The traffic light turned red, which was a signal for us to stop.
    • The smoke from the campfire was a signal for help.
  2. An electrical or radio wave that carries information, such as for television, radio, or the internet.
    • My phone can't get a signal in this remote area.
    • The radio signal was strong enough to reach the next town.
    • The TV lost its signal during the storm.
  3. An event or action that shows that something is likely to happen.
    • The first frost is often a signal that winter is coming.
    • The company's falling profits were a signal that changes were needed.
    • His sudden silence was a signal that he was upset.
Antonyms
verb
  1. To make a sign, gesture, or sound to give information or instructions.
    • The police officer signaled for the cars to stop.
    • The captain signaled the crew to prepare for departure.
    • She signaled to her friend across the room by waving.
  2. To indicate or show something clearly.
    • The dark clouds signal that a storm is on the way.
    • The results of the test signal a possible problem with the engine.
    • His smile signaled that he was happy with the news.
adjective
  1. Important or noticeable in a way that attracts attention.
    • The team made a signal improvement in their performance this season.
    • The discovery was a signal achievement for the scientists.
    • Her speech was a signal moment in the history of the organization.