Definition of "ternary"

ternary

/ˈtɜː.nə.ɹi/

adjective
not comparable
1. Made up of three things.
2. Arranged in groups of three.
3. (arithmetic) To the base three.
  Quotations
  Perhaps the prettiest number system of all is the balanced ternary notation
  1999, Donald Knuth, The Art of Computer Programming, 3rd edition, volume 2, page 207
4. (arithmetic) Having three variables.
5. (chemistry) Containing, or consisting of, three different parts, as elements, atoms, groups, or radicals, which are regarded as having different functions or relations in the molecule.
noun
plural ternaries
1. A group of three things; a trio, threesome or tierce.
2. (obsolete) The Holy Trinity.
  Quotations
  And albeit these thynges be waighty and truthes of great importance, yet (by the infinite goodnes of the Almighty Ternarie,) Artificiall Methods and easy wayes are made, by which the zelous Philosopher, may wyn nere this Riuerish Ida, this Mountayne of Contemplation […] .
  1570, John Dee, in H. Billingsley (trans.) Euclid, Elements of Geometry, Preface