echo stands for nothing.. echo stands for echo.. but echo means is to return. a sympathetic or identical response.
echo doesn't stand for anything in specific, but it is a language construct. http://en.wikipedia.org/wiki/Language_construct
An echo is a sound which is caused by a noise being reflected off a surface such as a wall. and in programming aspects you have been answered already
An echo is a reflection of sound, you make a noise and later it returns back to you (repeating). They say a duck's quack barely echoes or is hard to hear. One of the best words is two symbols words like 'eck-cho' so I guess thats why they called it an echo.