Meaning

• Administration, or administrative work.

  "There's a lot of admin involved in the birth of a child."

• A systems administrator; one who maintains a computer system or network.

  "Our admin has upgraded the server in our office, so we can exchange files faster."

• A user of a discussion forum, web site, etc. with privileges allowing them to control or restrict the activity of other uses.

  "The admin changed the forum settings to enable the use of emoticons."

Meaning

• To serve as an administrator for or of.