Unwanted sound in an engine 

noun

1. A sharp sound like that of a striking bullet
2. Knock
3. The pulse of sound waves reflected from or emitted by a submerged object in submarine signaling or detection and heard by special apparatus

   "Baylor … trained his sound unit from one bearing to another, listening for submarines. It threw out a directional sound beam, a series of "pings." These pings, if they hit a solid object like a submarine, reflected back to the operator."

4. A signal sent from one computer to another across a network for usually diagnostic purposes (as to determine network speed or the status of the target computer)

   "With Napster, however, all you have to do is type in the name of the song or artist and up will pop 2,745 Phish songs sorted by the host computer's type of modem connection and ping rate."

verb

1. To make a ping
2. To ricochet with a ping

   "gravel pinging off … the car"

3. To cause to ping

   "ping a bell"

4. To locate (something, such as a submerged object or submarine) by detecting the reflection of a pulse of sound waves to send out a ping see ping in order to locate (something)

   "We will have to follow this big old boy on the surface and then try to ping him with the sonar when he dives."

5. To send a signal to (a computer) in order to determine its status or the status of the connecting network

   "Without realizing what he was doing, he pinged every server in a .gov domain. Next day, his ISP canceled his account; the retribution was swift and uncompromising."

6. To send a signal to (a device, such as a cell phone) in order to determine its status or location

   "Howell officers warned police agencies across the state. … Police pinged the man's phone to get its location."

7. To send a usually brief message (such as a text message) or notification to (a person, a person's phone, etc.)

   "… provides an opportunity to check the time or see who pinged you while you were coming down the mountain …"

geographical name

1. River 360 miles (579 kilometers) long in western Thailand flowing south-southeast to join the Nan River forming the Chao Phraya River

verb

1. Shift, bounce

noun

1. Something resembling a game of table tennis

trademark

1. Used for table tennis

biographical name

1. 1904–1997 Chinese Communist leader (1977–97)

geographical name

1. City in Jilin province, northeastern China, southwest of Changchun population 509,000