Definition of ballon-sonde in English:

ballon-sonde

noun

Meteorology
historical
  • A small balloon used to carry instruments for recording atmospheric conditions into the upper atmosphere; a weather balloon, a sounding balloon.

Origin

Late 19th century; earliest use found in Science. From French ballon-sonde from ballon + sonde.

Pronunciation

ballon-sonde

/ˌbalɒnˈsɒnd/