The word 'ternary' has a direct and logical lineage from the Latin concept of three. It originates from the Latin ternarius, meaning "consisting of three," which itself derives from terni, the distributive form of tres (three). The suffix -arius, indicating pertaining to or connected with, was attached to form the adjective. This etymological path is straightforward, with the core meaning of "three" remaining central as the word evolved into English to describe anything composed of three parts, from musical forms to chemical compounds and, later, the base-three numeral system in computing.

Structure: tern (three) + ary (adjective suffix) "tern" is from Latin ternarius (consisting of three), from terni (three each), from tres (three). "ary" is an adjective-forming suffix from Latin -arius.