Noun
1. an event that departs from expectations
2. (biology) a group of organisms within a species that differ in trivial ways from similar groups;
"a new strain of microorganisms"3. a variable quantity that is random
4. something a little different from others of the same type;
"an experimental version of the night fighter""an emery wheel is a modern variant of the grindstone""the boy is a younger edition of his father"