ephemerally C2+

/ɪˈfɛmərəli/ in a way that lasts for a very short time M S

ephemeralness C2+

/əˈfɛmərəlnəs/ the quality of lasting for a very short time M S

ephemeron C2+

/əˈfɛmərɑn/ a short-lived thing, such as a mayfly or transient publication M S

nychthemeral C2+

/nɪkˈθɛmərəl/ relating to a full period of a day and a night (24 hours) M S