Informal Troublesome; annoying: a pesky mosquito. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "pesky" in a sentence
"The obvious result, if this type of suit becomes successful and pesky, is of course for media to start blocking Internet traffic from British URLs."
"They are up to their pinstripes in pesky rattlesnakes."
"I just tend to dislike certain pesky things like the "droit du seigneur" (did I spell that right?"