Real Dictionary

junk
Junk is old and used goods that have little value and that you do not want any more.
Junk refers to unwanted emails that have been sent to a large number of people or organizations, usually as advertising.

junk in American English 1
old cable or rope used for making oakum, mats, etc.
to throw away as worthless or get rid of by selling as junk; discard; scrap
adjective: cheap, worthless, unwanted, or trashy
noun: any old or discarded material, as metal, paper, or rags
transitive verb: to cast aside as junk; discard as no longer of use; scrap

junk in American English 2
a Chinese or Japanese flat-bottomed ship with a high stern and lugsails or lateen sails
noun: a seagoing ship with a traditional Chinese design and used primarily in Chinese waters, having square sails spread by battens, a high stern, and usually a flat bottom

junk in American English 3
noun: narcotics, esp. heroin

junk in British English 1
noun: discarded or secondhand objects, etc, collectively
verb: to discard as junk; scrap

junk in British English 2
noun: a sailing vessel used in Chinese waters and characterized by a very high poop, flat bottom, and square sails supported by battens