A
handgun firing mode where the action of
pulling the trigger does two things, mainly
cocking the hammer or
striker, and releasing it to ignite the cartridge.
Compare this to single action and to the newer safe action.
Double action semi auto pistols, unless they are DAO or double action only, implicitly have single action capability as well. If starting in condition 2 the first shot will be DA and the subsequent shots will be fired in SA mode.