" momentousness "

1: the quality or state of being important;

  * e.g., " ... no one could fail to realize the momentousness of the occasion "

•  Synonyms : 

•  account,

•  consequence,

•  import,

•  importance,

•  magnitude,

•  moment,

•  significance,

•  weight,

•  weightiness

•  Antonyms : 

•  insignificance,

•  littleness,

•  puniness,

•  slightness,

•  smallness,

•  triviality

1: having great meaning or lasting effect;

  * e.g., " ... a momentous occasion that will go down in the history books "

•  Synonyms : 

•  big,

•  consequential,

•  earth-shattering,

•  earthshaking,

•  eventful,

•  historic,

•  important,

•  major,

•  material,

•  meaningful,

•  monumental,

•  much,

•  significant,

•  substantial,

•  tectonic,

•  weighty

•  Antonyms : 

•  inconsequential,

•  inconsiderable,

•  insignificant,

•  little,

•  minor,

•  negligible,

•  slight,

•  small,

•  trifling,

•  trivial,

•  unimportant