from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Not active or tending to be active.
  • adjective Not functioning or operating; out of use.
  • adjective Not being in continuous use or operation.
  • adjective Retired from duty or service.
  • adjective Chemistry Not readily participating in chemical reactions; inert.
  • adjective Medicine Marked by the absence or lessening of disease activity.
  • adjective Physics Showing no optical activity in polarized light.

from The Century Dictionary.

  • In chem., causing no rotation in the plane of polarized light.
  • Not active or acting.
  • Marked by inaction or sluggishness; destitute of activity: as, an inactive existence; the inactive stage of insect life (that is, the period of metamorphosis, generally passed in concealment). Synonyms Inert, Lazy, etc. (see idle), passive, supine.

from the GNU version of the Collaborative International Dictionary of English.

  • adjective Not active; having no power to move; that does not or can not produce results; inert.
  • adjective Not disposed to action or effort; not diligent or industrious; not busy; idle.
  • adjective (Chem. & Opt.) Not exhibiting any action or activity on polarized light; optically inactive; optically neutral; -- said of isomeric forms of certain substances, in distinction from other forms which are optically active.
  • adjective (Chem. & Biochem.) Lacking biological or biochemical activity; not causing a specific biological or biochemical effect; -- said of substances such as enzymes which have lost their catalytic power, or of small molecules which are tested for some type of biological activity and found to lack that activity.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • adjective Not active, temporarily or permanently
  • adjective Not functioning or operating; broken down
  • adjective Retired from duty or service
  • adjective chemistry Relatively inert
  • adjective physics Showing no optical activity in polarized light

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adjective (chemistry) not participating in a chemical reaction; chemically inert
  • adjective (military) not involved in military operations
  • adjective lacking in energy or will
  • adjective (pathology) not progressing or increasing; or progressing slowly
  • adjective not exerting influence or change
  • adjective not engaged in full-time work
  • adjective not in physical motion
  • adjective (of e.g. volcanos) not erupting and not extinct
  • adjective lacking activity; lying idle or unused
  • adjective not active physically or mentally


from Wiktionary, Creative Commons Attribution/Share-Alike License

From in- +‎ active


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