Greek ephēmeros lasting a day, daily, from epi- + hēmera day
Ephemeral things (from Greek εφήμερος – ephemeros, literally "lasting only one day") are transitory, existing only briefly. Typically the term is used to describe objects found in nature, although it can describe a wide range of things.
In computer networking technology, an ephemeral port is a TCP, UDP or SCTP port which is dynamically assigned to a client application for a short period of time (the duration of time the application is running). This is in contrast to the "well known" ports which are typically statically assigned to a specific application or service.
In philosophy, Denis Diderot makes use of the term "Fallacy of the Ephemeral," which refers to assumptions made outside of one's scope of time, perception, or knowledge. "...in the memory of a rose no one had ever seen a gardener die". From Diderot's Le rêve de D'Alembert.
The peace of God is shining in you now, and from your heart extends around the world. It pauses to caress each living thing, and leaves a blessing with it that remains forever and forever. What it gives must be eternal. It removes all thoughts of the ephemeral and valueless. It brings renewal to all tired hearts, and lights all vision as it passes by. All of its gifts are given everyone, and everyone unites in giving thanks to you who give, and you who have received. - (ACIM Lesson 188)