Synonyms for Insignificance:

adj.

unsubstantial (adjective)
apparitional, chimerical, empty, ethereal, illusory, immaterial, impalpable, inessential, intangible, null, phantasmal, spectral, tenuous, unreal, unsubstantial, vacant, vacuous, weightless, unconcrete, nonexistence.

n.

concern, indifference, Inconsequentiality, Insignificancy, inconsequentialness. indifference (noun)
inconsequence, Inconsequentiality, Insignificancy, inconsequentialness.
unimportance (noun)
banality, frivolity, futility, immateriality, inconsequence, indifference, insipidity, irrelevance, meanness, minutia, molehill, nothingness, paltriness, pettiness, smallness, triteness, trivia, triviality, unimportance, vanishing point, vanity, worthlessness, Inconsequentiality, triflingness, negligibility, trifling matter.
unsubstantiality (noun)
apparition, cipher, emptiness, immateriality, impalpability, intangibility, mirage, nonexistence, nothingness, nullity, phantom, spectre, unreality, vacancy, vacuity, zero, Ethereality, Nihility, tenuousness.

Other synonyms:

Inconsequentiality, Insignificancy, inconsequentialness. indifference. pettiness
paltriness.
Other relevant words:
concern, frivolousness, futility, indifference, meanness, molehill, paltriness, pettiness, smallness, subordination, subservience, superficiality, triviality, vanity, worthlessness, Inconsequentiality, Insignificancy, negligibility, inconsequentialness, trifling matter.

Usage examples for insignificance

  1. A single false step, an hour's weakness of purpose, nay, even a failure for which he was not himself accountable in home or foreign policy, might deprive him of his influence over the majority, and might reduce him to comparative insignificance – A History of the Four Georges, Volume I (of 4) by Justin McCarthy
  2. Before this line the question whether there is a connection between the Tanganika and the Albert N'Yanza sinks into insignificance – How I Found Livingstone by Sir Henry M. Stanley
  3. Lesurques' mother died of grief; his wife went mad; his three children languished in insignificance and poverty. – The Buried Temple by Maurice Maeterlinck