lubricant
n.
1828, probably from lubricant, adj., or from Latin lubricantem.
adj.
"reducing friction," 1809, from Latin lubricantem (nominative lubricans), present participle of lubricare "to make slippery or smooth," from lubricus "slippery; easily moved, sliding, gliding;" figuratively "uncertain, hazardous, dangerous; seductive," from PIE *sleubh- "to slip, slide" (see sleeve).