periodical

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

• adjective Periodic.
• adjective Published at regular intervals of more than one day.
• adjective Of or relating to a publication issued at such intervals.
• noun A publication issued at regular intervals of more than one day.

from The Century Dictionary.

• Having a period; performed in a fixed period or cycle; appearing, occurring, or happening at stated intervals; regularly or statedly recurring at the end of a fixed period of time: as, periodical diseases; periodical publications.
• Of or pertaining to magazines, newspapers, or other publications which appear or are published at regularly recurring intervals.
• noun A publication issued at regular intervals in successive numbers or parts, each of which (properly) contains matter on a variety of topics, and no one of which is contemplated as forming a book by itself.

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

• noun A magazine or other publication which appears at stated or regular intervals.

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

• noun A publication issued regularly, but less frequently than daily
• noun A publication that appears at fixed intervals
• noun Often contains the most current information in the field, on every conceivable topic, often in greater detail than other publication formats.
• noun The primary means for communication of original scholarship or creative work at the cutting edge of research in almost all fields.
• adjective Periodic
• adjective Published at regular intervals of more than one day, especially weekly, monthly, or quarterly
• adjective Of, or relating to such a publication

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

• adjective happening or recurring at regular intervals
• noun a publication that appears at fixed intervals