WordDictionary

Noun:

• A high-pitched, short and somewhat sharp sound.
• text messaging|internet An email or other message sent requesting acknowledgement.
• submarine navigation A pulse of high-pitched or ultrasonic sound whose echoes provide information about nearby objects and vessels.
• networking A packet which a remote host is expected to echo, thus indicating its presence.

Verb:

• colloquial To flick.
• colloquial|sports|intransitive To bounce.
• colloquial|sports|transitive To cause something to bounce.
• submarine navigation To emit a signal and then listen for its echo in order to detect objects.
• networking To ping and receive an acknowledgement.
• networking To send a packet in order to determine whether a host is present, particularly by use of the ping utility.
• To make a high-pitched, short and somewhat sharp sound.
• To send an email or other message to someone in hopes of eliciting a response.