Dictionary:

Pashto

  (pŭsh'tō) also Pushtu (pŭsh'tū)

An Iranian language that is the principal vernacular language of Afghanistan and parts of western Pakistan. Also called Afghan.

[Persian pashtu, from Pashto pašto, perhaps ultimately from Iranian *parsāwa-, border, border people.]

An Indo-European language related to English but belonging to the eastern Indo-Iranian group. It is spoken today by 35-50% of the Afghani population. There is a high degree of bilingualism with Farsi. It is one of the two official languages taught in schools and used in radio programs. It is spoken mainly by Hanafi Sunni Muslims according to Ethnologue.

The noun has 2 meanings:

Meaning #1: a native or inhabitant of Afghanistan
  Synonyms: Afghan, Afghanistani, Pathan

Meaning #2: an Iranian language spoken in Afghanistan and Pakistan
  Synonyms: Paxto, Afghani, Afghan