brachylogy

/B R EY1 K AH0 L AH0 JH IY0/
noun
  1. 1

    Concise speech; laconism

  2. 2

    Any of several forms of omission of words, including the omission of an understood part of a phrase, as, the omission of "good" from "(good) morning!"

Source: https://en.wiktionary.org/wiki/brachylogy