Definition of code-share in US English:

code-share

verb

[no object]
  • (of airlines) enter into a commercial arrangement whereby one sells seats on a flight operated by the other, with each airline using their own flight number.

    ‘the two airlines will code-share on flights between the two countries’

noun

  • A commercial arrangement beween two airlines whereby one sells seats on a flight operated by the other, with each airline using their own flight number.

    ‘they're doing a code-share with Air India’
    as modifier ‘code-share flights’