Taciturn is a formal word that describes someone who tends to be quiet or who tends to speak infrequently.

// One of the twins was taciturn and shy, while the other one was more outgoing.

See the entry >

“Joan Didion looks straight at the camera, with her fist curled in front of her mouth—as if to indicate it is through her hands that the taciturn thinker speaks.” — Evelyn McDonnell, The World According to Joan Didion, 2023

Even if you consider yourself a person of few words, taciturn is a good one to keep in your pocket, if for no other reason than it’s an efficient way to describe your own particular deportment. While ramblers ramble and babblers babble, the taciturn among us turn things down a notch, preferring to keep mum rather than add their voices to the verbal hubbub. Taciturn traces back ultimately to the Latin verb tacēre, meaning “to be silent.” While English users were quicker to adopt other tacēre descendants such as the adjective tacit (“expressed without words” or “implied”) in the 1600s and even the noun taciturnity in the 1400s, taciturn wasn’t on anyone’s lips until the 1700s.