Definition of "ch"

ch¹

noun
countable and uncountable, plural chs
1. Abbreviation of chain, a unit of measurement equal to 22 yards
2. Abbreviation of chapter, main section of a book
  Quotations
  Ch 2 secondarily interrupts the flow between chs 1 and 3 (see 2.1–16n.).
  2007, The New Oxford Annotated Bible with the Apocryphal/Deuterocanonical Books, page 143
3. Abbreviation of chestnut, a dark reddish-brown colored horse
  Quotations
  NAME OF HORSE (COLOR, SEX, YEAR BORN)Secretariat (ch.s. 1970)
  2014, Kenneth Hinchcliff, Andris Kaneps, Raymond Geor, Equine Sports Medicine and Surgery, page 675
4. Abbreviation of channel, in reference to telephones, audio, radio, and television

ch²

/t͡ʃ/

pronoun
1. (obsolete, dialectal) Alternative form of I