Momentous describes an important event or moment in time. It is used for a time of great consequence or for a major accomplishment, and is almost always reserved for good things.

When a moment is so great you know you'll never forget it, you have just experienced something momentous. It can be personal — perhaps the day you were named prom queen; or something historic — like the day Elizabeth was named Queen of England. Momentous and momentary share the root word moment but momentary describes just one fleeting moment in time. A momentary occurrence can certainly be momentous, but it's not always the case.

Definitions of momentous
  1. adjective
    of very great significance
    “a momentous event”
    important, significant
    important in effect or meaning
Word Family