6S

6S may stand for:


 * 6S (music), key signature of six sharps
 * 6S (radiative transfer code), a computer program that simulates the reflection of solar radiation
 * 6S / SsrS RNA, the first noncoding RNA to be sequenced
 * 6S, a modification of the 5S methodology which includes "Safety" as the 6th S. It is a lean process improvement tool that stands for Sort, Set in Order (aka Straighten or Stabilize), Shine (aka Scrub or Sweep), Standardize, Sustain, Safety.
 * 6S can be the shortened form of Six Sigma
 * iPhone 6S, a smartphone by Apple, Inc.
 * 6S, the production code for the 1984 Doctor Who serial The Twin Dilemma

Transportation

 * Kato Airline, a Norwegian airline with an IATA airline designator of 6S from 1996 to 2008
 * Sahara Airlines (Algeria), an Algerian airline with an IATA airline designator of 6S from 1999 to 2003
 * British Rail Class 201 diesel-electric multiple units with 6 coaches and a short frame (6S)