[originally among Amiga fans]
1. Synonym for luser, not used much by hackers but common among warez d00dz, crackers, and phreakers. A person who downloads much, but who never uploads. (Also known as leecher). Oppose elite. Has the same connotations of self-conscious elitism that use of luser does among hackers.
2. Someone who tries to crack a BBS.
3. Someone who annoys the sysop or other BBS users — for instance, by posting lots of silly messages, uploading virus-ridden software, frequently dropping carrier, etc.
Crackers also use it to refer to cracker wannabees. In phreak culture, a lamer is one who scams codes off others rather than doing cracks or really understanding the fundamental concepts. In warez d00dz culture, where the ability to wave around cracked commercial software within days of (or before) release to the commercial market is much esteemed, the lamer might try to upload garbage or shareware or something incredibly old (old in this context is read as a few years to anything older than 3 days). ‘Lamer’ is also much used in the IRC world in a similar sense to the above.
This term seems to have originated in the Commodore-64 scene in the mid 1980s. It was popularized among Amiga crackers of the mid-1980s by ‘Lamer Exterminator’, the most famous and feared Amiga virus ever, which gradually corrupted non-write-protected floppy disks with bad sectors. The bad sectors, when looked at, were overwritten with repetitions of the string “LAMER!”.