From The Free On-line Dictionary of Computing (05 Sep 00):

A popular distributed document retrieval system which started as a Campus Wide Information System at the University of Minnesota. Many hosts on the Internet now run Gopher servers which provide a menu of documents. A document may be a plain text file, sound, image, submenu or other Gopher object type. It may be stored on another host or may provide the ability to search through certain files for a given string.

From Jargon File (4.2.0, 31 Jan 2000):

gopher n. A type of Internet service first floated around 1991 and obsolesced around 1995 by the World Wide Web. Gopher presents a menuing interface to a tree or graph of links; the links can be to documents, runnable programs, or other gopher menus arbitrarily far across the net.

Some claim that the gopher software, which was originally developed at the University of Minnesota, was named after the Minnesota Gophers (a sports team). Others claim the word derives from American slang `gofer' (from "go for", dialectal "go fer"), one whose job is to run and fetch things. Finally, observe that gophers dig long tunnels, and the idea of tunneling through the net to find information was a defining metaphor for the developers. Probably all three things were true, but with the first two coming first and the gopher-tunnel metaphor serendipitously adding flavor and impetus to the project as it developed out of its concept stage.