Source : Webster's Revised Unabridged Dictionary (1913)

Inaction \In*ac"tion\, n. [Pref. in. not + action: cf.
   inaction.]
   Want of action or activity; forbearance from labor; idleness;
   rest; inertness. --Berkeley.

Source : WordNet®

inaction
     n 1: the state of being inactive [syn: {inactivity}, {inactiveness}]
          [ant: {action}, {action}, {action}]
     2: a state of no activity [syn: {inactiveness}]