different between quiescence vs quiescency

English

quiescent +? -ence, or borrowed from Latin quiescentia, from quiescens, present participle of quiesco, from quies.

quiescence (countable and uncountable, plural quiescences)

The state of being quiescent; dormancy.
Being at rest, quiet, still, inactive or motionless.
The action of bringing something to rest or making it quiescent; the action of coming to rest or to a quiescent state.
- 1662 Thomas Salusbury, Galileo's Dialogue Concerning the Two Chief World Systems, Dialogue 2:
  I pray you, Salviatus, to tell me ... the cause of the Pendulum's quiescence.
(microbiology) The period when a cell is in a term of no growth and no division.
(entomology) In insects, a temporary slowing down of metabolism and development in response to adverse environmental conditions, which, unlike diapause, does not involve physiological changes.

From Latin quiescentia

quiescency (uncountable)

Classified by Garner as a "needless variant" of quiescence: Garner's Modern American Usage, Dictionary of Modern Legal Usage

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