Of or pertaining to high frequency sound or other radiation. / Occurring or doing something very frequently.

plural of high school

Having a great risk.

(athletics) An athlete who competes in the high jump.

(US) A light-skinned black person.

(simile, colloquial) Very much under the influence of drugs; extremely high.

At an important, elevated, or exalted level in a hierarchy or organization; high-level.

(usually in the plural) The setting of an automobile's headlights adjusted to brighten a longer distance in front of the car, than when on the normal (low-beam) setting.

In a high-minded manner.

(Britain) Alternative letter-case form of high street