Real Dictionary

vista
countable noun: A vista is a view from a particular place, especially a beautiful view from a high place.
countable noun: A vista is a vision of a situation or of a range of possibilities.

VISTA in American English
a U.S. government program established in 1964 to provide volunteers to work at improving the living conditions of persons in impoverished areas of the U.S., its possessions, and Puerto Rico
a view or outlook, esp. one seen through a long passage, as between rows of houses or trees
noun: a national program in the U.S., now part of the AmeriCorps network of programs, for sending volunteers into underprivileged areas to teach various job skills
noun: a view or prospect, esp. one seen through a long, narrow avenue or passage, as between rows of trees or houses

vista in British English
noun: a view, esp through a long narrow avenue of trees, buildings, etc, or such a passage or avenue itself; prospect
noun acronym for: Volunteers in Service to America; an organization of volunteers established by the Federal government to assist poor people