'Microseism' definitions:

Definition of 'microseism'

(from WordNet)
noun
A small earthquake [syn: tremor, earth tremor, microseism]

Definition of 'Microseism'

From: GCIDE
  • Microseism \Mi"cro*seism\, n. [Micro- + Gr. ? an earthquake, fr. ? to shake.] A feeble earth tremor not directly perceptible, but detected only by means of specially constructed apparatus. -- {Mi`cro*seis"mic}, {Mi`cro*seis"mic*al}, a. [Webster 1913 Suppl.]