Occurring without periodicity; irregular.(adjective)
Physics Without periodic vibrations.(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 "aperiodic" in a sentence
"Some trajectory orbits are aperiodic, meaning that they do not repeat themselves on any time scales."
"Schrödinger proposed that a gene could be stable from one generation to another if it is an 'aperiodic' crystal – in other words, something with a regular but non-repeating structure."
"But life is characterized by specified complexity: the aperiodic, information-rich sequences of DNA and proteins, for instance, which appear nearly random to standard information theory."