DEFINITIONS:
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2000 by Houghton Mifflin Company

To fish for by trailing a baited line from behind a slowly moving boat.

To fish in by trailing a baited line: troll the lake for bass.

To trail (a baited line) in fishing.

A supernatural creature of Scandinavian folklore, variously portrayed as a friendly or mischievous dwarf or as a giant, that lives in caves, in the hills, or under bridges.

Slang. To patrol (an area) in search for someone or something: “ [Criminals] troll bus stations for young runaways.”

Music.
To sing in succession the parts of (a round, for example).

To sing heartily: troll a carol.

To roll or revolve.

SYNONYMS:
Roget's New Millennium™ Thesaurus, First Edition (v 1.1.1)

rascal, brat, demon, devil, deviling, devilkin, elf, fiend, gamin, gnome, gremlin, hellcat, hellion, minx, pixie, puck, rascal, rogue, scamp, sprite, troll, tyke, urchin, villain

For a picture of a troll, I went to www.askjeeves.com...

Hope this helps...