Insignificant

Antonyms of insignificant:
important, significant, remarkable, probatory, epoch-making, probative, profound, major, monumental, noticeable, operative, fundamental, earthshaking, momentous, large, evidential, epochal, world-shattering, world-shaking, evidentiary, meaningful, prodigious, noteworthy, portentous, decisive, fatal, fateful, chief, dominant, overbearing, overmastering, overriding, principal, distinctive, exceptional, impressive, outstanding, prominent, valuable, worthwhile, worthy, distinguished, eminent, great, illustrious, preeminent, prestigious, famous, notorious, renowned, all-important, basic, essential, key, big, consequential, eventful, material, substantial, unfrivolous, weighty, serious, pivotal, conspicuous, striking, appreciable, discernible, measurable, considerable.
Examples of usage:
  1. Well, he's rather too insignificant for me.
    "The Complete Project Gutenberg Works of George Meredith", George Meredith.
  2. From a modern architectural point of view, they would at first seem quite insignificant, and yet, hidden away beneath the rough exteriors, there are often interesting lines and good proportions.
    "Remodeled Farmhouses", Mary H. Northend.
  3. Of the Corots, twelve in number, we did not see an insignificant one, not a weak one.
    "Promenades of an Impressionist", James Huneker.