Back when I was growing up, DEW weapons were called "Phasers".

According to the "The Making of Star Trek", by Gene Roddenberry and Stephen Whitfield,

"All phasers emit a beam of energy similar to the light beam emitted by a laser, but of a pulsating nature that can be 'phased' to interfere or interact with the wave pattern of any molecular form. Phaser beams can be fire steadily, or in intermittent 'squirts' or 'phased' energy. They can be set to 'dematerialize', (converting matter into energy), 'disrupt' (breaking down matter), or 'stun' (neural impact)"

It's a fancy way of saying it's a tactical laser with an added property: the ability to destroy matter at the sub-molecular level by agitating the atoms directly. A disintegration ray.