lubricant (n.)

"material that can reduce friction in rubbing surfaces," 1828, probably from lubricant (adj.), or else from Latin lubricantem.

"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 *leubh-ro-, suffixed form of root *sleubh- "to slip, slide."