Oubliette
Oubliette , noun
[French, from oublier to forget, from (assumed) Late Latin oblitare, Latin oblivisci, p. p. oblitus.]
A dungeon with an opening only at the top, found in some old castles and other strongholds, into which persons condemned to perpetual imprisonment, or to perish secretly, were thrust, or lured to fall.
Sudden in the sun
An oubliette winks. Where is he? Gone.