Blinking implies an on and off cycle by design. Flashing implies a brief cycle of on or brightness, followed by a period of off, both uncontrolled, however in some specialized instances "flashing" is used for controlled cycles. "Blink" is a Germanic word, "flash"--I didn't check the etymology. Flickering implies random short periods of on and off, completely random and uncontrolled. Short= perhaps 1-2 Hz or greater.