Definitions of variant:

• noun:   something a little different from others of the same type

  Example: "An emery wheel is a modern variant of the grindstone"

• noun:   (biology) a group of organisms within a species that differ in trivial ways from similar groups
• noun:   a variable quantity that is random
• noun:   an event that departs from expectations
• adjective:   differing from a norm or standard

  Example: "A variant spelling"