A

The prefix “a” works in a similar manner to “in” and, depending on the context, it can mean “on”, “in”, “at” or “together”, but most often it means “not”.
Such as:
  • Asymptomatic - no symptoms.
  • Amoral – no morals.
  • Asleep – “in” sleep.
  • Alive – “in” live or life.