Luciferin (j)

Adventures in Logophilia, Day 148:

luciferin (n)

Luciferin is the natural substance present in certain organisms that produce heatless light upon oxidation - like fireflies.  This is from the Latin word "lucifer" meaning "light-bearing," and, yes, is also the name of the Devil.  Ironic, no?

Unctuous (j)

Adventures in Logophilia, Day 147:

unctuous (adj)

Greasy, oily, smug.  Falsely earnest.  The cigarette-smoking man (The X-Files).  Thomas Barrow (Downton Abbey). The Master (Doctor Who). 

Repose (j)

Adventures in Logophilia, Day 146:

repose (n)

Repose is sleep, often used to mean eternal or heavenly rest.  It also means calm or peace in an absence of activity or movement.  Composure.  Poise.