intermittent

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Stopping and starting at intervals. synonym: periodic.
• adjective Alternately containing and empty of water.

from The Century Dictionary.

• Ceasing at intervals; that alternately stops and starts; intermitting: as, an intermittent fever; an intermittent spring.
• noun Intermittent fever.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Coming and going at intervals; alternating; recurrent; periodic.
• adjective (Med.) a disease with fever which recurs at certain intervals; -- applied particularly to fever and ague. See Fever.
• adjective (Mach.) gearing which receives, or produces, intermittent motion.
• adjective springs which flow at intervals, not apparently dependent upon rain or drought. They probably owe their intermittent action to their being connected with natural reservoirs in hills or mountains by passages having the form of a siphon, the water beginning to flow when it has accumulated so as to fill the upper part of the siphon, and ceasing when, by running through it, it has fallen below the orifice of the upper part of the siphon in the reservoir.
• noun (Med.) An intermittent fever or disease.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Stopping and starting at intervals; coming after a particular time span; not steady or constant
• adjective specifically, geology, of a body of water Existing only for certain seasons; that is, being dry for part of the year.
• noun medicine, dated An intermittent fever or disease.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective stopping and starting at irregular intervals