pe·riph·er·al (p?-r?f??r-?l)adj.1. Related to, located in, or constituting an outer boundary or periphery.2. Perceived or perceiving near the outer edges of the retina: peripheral vision.3. Anatomy a. Of the surface or outer part of a body or organ; external.b. Of, relating to, or being part of the peripheral nervous system.4. Of minor relevance or importance.5. Auxiliary.n. Computers An auxiliary device, such as a printer, modem, or storage system, that works in conjunction with a computer.pe·riph?er·al·ly adv.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.peripheral (p??r?f?r?l) adj1. not relating to the most important part of something; incidental, minor, or superficial2. of, relating to, or of the nature of a periphery3. (Anatomy) anatomy of, relating to, or situated near the surface of the body: a peripheral nerve. Also: peripheric or peripherical pe?ripherally advCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014pe?riph?er?al (p??r?f ?r ?l) adj. 1. pertaining to or constituting the periphery. 2. concerned with the minor or superficial aspects of a question. 3. Anat. near the surface or outside of; external. 4. of or pertaining to a computer peripheral. n. 5. an external hardware device, as a keyboard, printer, or tape drive, connected to a computer’s CPU. [1800?10;