Light amplification by stimulated emission of radiation.
Lasers produce a concentrated beam of energy. Many different powers and wavelengths of laser radiation are used for measurement or as a surgical instrument. Their usefulness and their dangers to the operator, bystanders and patient are more subtle than those of a knife.
Laser injuries particularly to the eye may arise in warfare or industry. Eye injuries by powerful lasers are likely to be total in less time than the blink reflex.