ABCs

noun[plural only]4

1. •
   (US) The alphabet.

   • Do you know your ABC? (U.S.: Do you know your ABCs?)
2. •
   The alphabet, especially the English alphabet.
3. •
   Letters; writing; the skill of literacy.

   • He was busy learning his ABCs.
4. •
   (no longer used) A type of poem in which the lines start with the letters of the alphabet in order.