binary
1. [ adjective ] consisting of two (units or components or elements or terms) or based on two
Examples:

"a binary star is a system in which two stars revolve around each other" "a binary compound" "the binary number system has two as its base"

Related terms: multiple
2. [ adjective ] of or pertaining to a number system have 2 as its base
Examples:

"a binary digit"

Related terms: binary_numeration_system
3. [ noun ] (astronomy) a system of two stars that revolve around each other under their mutual gravitation
Synonyms: double_star binary_star
Related terms: star Antares Aldebaran Epsilon_Aurigae Rigel Algol Procyon Vega Alpha_Centauri altair Sirius