Echo

Echo most commonly refers to Echo (phenomenon), the reflection of a sound.

It may also refer to:

Science and technology

Echo satellite, one of the first communications satellites
EChO, a proposed European Space Agency mission to study exoplanet atmospheres.
Echo sounding, a way to measure water depth
Light echo, a visual phenomenon
Signal reflection, a concept in telecommunications
ECHO Clearinghouse, NASA's registry of Earth Science data and services, an early SOA example

Echo (command), a Unix, DOS and Microsoft Windows command to display a line of text
Echo (computing), a feature of telecommunications protocols
Echo (framework), a web framework for Java programming
The Echo Protocol, an Internet protocol largely superseded by ICMP
A command in programming languages to output one or more strings
A discussion forum on FidoNet

ECHO (echocardiography), an imaging technique used to assess heart function in medicine
Echovirus, short for "enteric cytopathic human orphan" virus
echo-, involuntary repetition or imitation, as in echolalia and echopraxia

Echo (mythology), a nymph
Echo (Marvel Comics), a superheroine in the Marvel universe
Echo (DC Comics) - a name that has been used by a number of different characters in works published by DC Comics.
- Query and Echo, the team of henchmen for the Riddler that featured the fifth character in DC Comics named "Echo"
Echo (Dollhouse), the protagonist of science-fiction TV series Dollhouse
Echo (comic book), a comic book title by Terry Moore, launched in 2008
Echo (1997 film), a 1997 TV film
Echo (2003 film), a 2003 short film directed by Tom Oesch
Echo (2007 film), a 2007 Danish film
Echo: Secrets of the Lost Cavern, a video game
A race of aliens from the UK TV series Invasion: Earth (TV series)
Echo Nightray (Anime and Manga) is a female character in the anime and manga Pandora Hearts

"Echo" (Gorilla Zoe song)
"Echo" (Trapt song)
"Echo" (Ciara song)
"Echo" (R. Kelly song)
"Echo" (Girls Can't Catch song)
"Echo", a song by Cyndi Lauper from the album Bring Ya to the Brink
"Echo" a song by Bad Meets Evil (Eminem & Royce Da 5'9), from the deluxe edition of Hell: The Sequel album.
"Echo" by Girls' Generation

ECHO (European Commission), a department of the European Union
Extended Care Health Option, a health coverage program
Echo (radio station), a community radio station in Farnborough, Hampshire
Echo of Moscow, a Russian radio station
ECHO Lake Aquarium and Science Center, an interactive museum and research center in Burlington, Vermont

Echo Incorporated, a manufacturer of chainsaws, trimmers and other small-engine machines.
Echo Johnson, a model and actress
60 Echo, an asteroid
Toyota Echo, a car
Echo smartpen, a ballpoint pen, computer, and audio recorder manufactured by Livescribe
A letter in the NATO phonetic alphabet
The title of a poem by Christina Rossetti
An old-fashioned South Australian term for "bottle".
Echo, a famous matriarch elephant in the Amboseli National Park
Echo (genus), a genus of damselfly
Kyocera Echo, a dual screen smart phone