twosome

Short definition from Wiktionary

Adjective

1. 1
   Being or constituting a pair; two.
2. 2
   Twofold; double.
3. 3
   Performed by two individuals.

Noun

1. 1
   A group of two; a pair; a couple; a group of two distinct individuals or components.
2. 2
   A dance for two people.