ephemeral vs fugacious

ephemeral is a noun but fugacious is not a noun.

Word	Noun	Adjective	Verb	Adverb
ephemeral	Yes	Yes	No	No
fugacious	No	Yes	No	No

As adjectives, ephemeral and fugacious are synonyms defined as:

Other synonyms of ephemeral include passing, short-lived, transient, transitory.

ephemeral (noun)	fugacious (noun)
anything short-lived, as an insect that lives only for a day in its winged form

ephemeral (adjective)	fugacious (adjective)
lasting a very short time	lasting a very short time