savoir-faire (n.)

"instinctive knowledge of the right course of action in any circumstance," 1815, from French, literally "to know (how) to do," from savoir "to know" (from Latin sapere; see sapient) + faire (from Latin facere "to make, do;" from PIE root *dhe- "to set, put"). French also has savoir-vivre "ability in good society; knowledge of customs in the world."