lacuna
dictionary.com:
n. pl. la·cu·nae (-n) or la·cu·nas
1. An empty space or a missing part; a gap: “self-centered in opinion, with curious lacunae of astounding ignorance” (Frank Norris).
2. Anatomy. A cavity, space, or depression, especially in a bone, containing cartilage or bone cells.
miasma
dictionary.com:
n. pl. mi·as·mas or mi·as·ma·ta (-m-t)
1. A noxious atmosphere or influence: “The family affection, the family expectations, seemed to permeate the atmosphere... like a coiling miasma” (Louis Auchincloss).
2.
1. A poisonous atmosphere formerly thought to rise from swamps and putrid matter and cause disease.
2. A thick vaporous atmosphere or emanation: wreathed in a miasma of cigarette smoke.
From: The Epicure's Lament, Kate Christensen, p 8
"I stopped writing once again after that last sentence, and stared off into space for... a lacuna, a miasma, a hiatus, an unwieldy string of vowel's worth of time"