aperiodic

adjective

1. not periodic; irregular.
2. Physics. of or relating to vibrations or oscillations with no apparent period.

adjective

1. not periodic; not occurring at regular intervals
2. physics
   1. (of a system or instrument) being damped sufficiently to reach equilibrium without oscillation
   2. (of an oscillation or vibration) not having a regular period
   3. (of an electrical circuit) not having a measurable resonant frequency

adj.

1. Not occurring periodically.