fugitive

fugitive \FYOO-ji-tiv\, adjective:

1. Fleeting, transitory, elusive.
2. Having taken flight, or run away.
3. Changing color as a result of exposure to light and chemical substances present in the atmosphere, in other pigments, or in the medium.
4. Dealing with subjects of passing interest, as writings; ephemeral.
5. Wandering, roving, or vagabond.

I started to write about Sean, and the writing, like a searchlight sweeping wildly, almost caught my fugitive feelings.
-- Edmund White, The Beautiful Room Is Empty

I fill my own glass now, and raise it, unspeaking: to her? to us? to the spirit of fugitive love? Whatever it is I mean, she nods as if to say she understands.
-- Vikram Seth, An Equal Music

First used by Shakespeare in Antony & Cleopatra, fugitive stems from the Latin word fugere meaning "to flee."