Lacuna

lacuna |ləˈk(y)oōnə| ( pl. -nae or -nas )
noun
1. an unfilled space or interval; a gap.
2. a missing portion in a book or manuscript.
3. (anatomy) a cavity or depression, esp. in bone.

[ORIGIN mid 17th cent.: from Latin, ‘pool,’ from lacus ‘lake.’]

Noetic

noetic
-adjective
of or relating to mental activity or the intellect.

[ORIGIN mid 17th cent.: from Greek noētikos, from noētos ‘intellectual,’ from noein ‘perceive.’]

Tenebrific

tenebrific
–adjective

serving to obscure or darken; gloomy; dark; producing darkness.

[ORIGIN: 1640–50 from Latin tenebr(ae), darkness, + -i- + -fic]