IPA: //moʊˈmɛn.tə.ri.nəs//
KK: /moʊˈmɛntəˌrɪnəs/
The quality or state of lasting for a very short time.
The momentariness of the event made it feel even more special.
Momentariness → It is formed from "moment" (from Latin *momentum*, meaning a movement or a brief period of time) and the suffix "-ness" (meaning the state or quality of). The word "momentariness" refers to the quality of being momentary or temporary.
Think of a 'moment' as a brief period of time, and remember that 'momentariness' describes the quality of being temporary.