Answer:

rad

Answer	Crossword Clue
RAD	Cool, in the '90s
RAD	Energy unit
RAD	Extremist

RAD	"Awesome!"
RAD	Cool
RAD	Marvelous, slangily
RAD	One-half a diam.
RAD	Cool, these days
RAD	Physicist's unit
RAD	Totally awesome
RAD	Half a diam.

RAD	Way cool
RAD	Unit of nuclear absorption
RAD	Angle measurement (abbr.)
RAD	"Way cool!"
RAD	"Far out!"
RAD	"Totally tubular!"
RAD	"Wicked!"
RAD	Awesome, in kidspeak

RAD	Kewl
RAD	Awesome!
RAD	"Kewl!"
RAD	Skatepark "great"
RAD	Way cool!
RAD	Fantastic!
RAD	Excellent, slangily
RAD	Outstanding!

RAD	Surfspeak adjective
RAD	Alternative to degrees, in math: Abbr.
RAD	"Cool!"
RAD	"Super, man!"
RAD	X-ray unit
RAD	"Outstanding!"
RAD	"Groovy!"
RAD	Gnarly

RAD	Awesome
RAD	"Really cool!"
RAD	Groovy relative?
RAD	"Totally awesome!"
RAD	"Gnarly!"