BAS may stand for:
Most commonly:

• BASIC programming language, file extension

Bas meaning lower in French may refer to:

• Bas (name)
• Bas (rapper)

A Bachelor of Arts (BA, B.A., AB or A.B. from the Latin artium baccalaureus or baccalaureus artium) is a bachelor's degree awarded for an undergraduate course or program in either the liberal arts, the sciences, or both. Bachelor of Arts degree programs generally take three to four years depending on the country, academic institution, and specific specializations, majors or minors. The word baccalaureus or baccalarium (from the Latin bacca, a berry, and laureus, "of the bay laurel") should not be confused with baccalaureatus (translatable as "gold-plated scepter" by using the Latin baculum and aureatus), which refers to the one- to two-year postgraduate Bachelor of Arts with Honours degree (Baccalaureatus in Artibus Cum Honore) in some countries.

Barium sulfide is the inorganic compound with the formula BaS. BaS is an important precursor to other barium compounds including BaCO₃ and the pigment lithopone, ZnS/BaSO₄. Like other chalcogenides of the alkaline earth metals, BaS is a short wavelength emitters for electronic displays. It is colorless, although like many sulfides, it is commonly obtained in impure colored forms.