NOTE: doesn't occur as a plural, is a mass noun
Those two boxes of old papers are junk that can be thrown out.
John discarded an old sofa on the curb along with some other junk.
Rusted out cars and other junk lay abandoned along the highway.
WordNet 3.0 Sense Numbers: 1
NOTE: also a mass noun, implies current possession, not discarded things.
Let's clean up the junk in the living room before the guests arrive.
How can you find anything will all this junk on your desk?
John carries a ton of junk in his book bag.
WordNet 0.0 Sense Numbers: 2a-3
NOTE: can occur in the plural, -not- a mass noun
We saw many junks in the water as we approached Hong Kong.
There was a beautiful green junk in the annual Asian River Festival last year.
WordNet 3.0 Sense Numbers: 2
For years the musician was hooked on junk.
The street price for junk went up sharply after the big drug bust.
WordNet 0.0 Sense Numbers: 3
NOTE: functions as an attributive of some other noun or entity.
The state's bonds were downgraded to junk last month.
These designer jeans are junk, who would pay that price for them?
Be careful when buying junk bonds.
Mary thought his latest novel was junk.
WordNet 0.0 Sense Numbers: 2c
After two fastballs, the relief pitcher started throwing junk.
The batters have been swinging at some junk this inning.
WordNet 0.0 Sense Numbers: 5