savoir-faire (n.) Look up savoir-faire at Dictionary.com
"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;" see factitious). French also has savoir-vivre "ability in good society; knowledge of customs in the world."