What is the synonym of the word ‘Taciturn’?

Taciturn (ADJECTIVE):
Meaning: (of a person) reserved or uncommunicative in speech; saying little.
Synonym:
untalkative, uncommunicative, reticent, unforthcoming, quiet, unresponsive, secretive, reserved, introverted
Antonym:
talkative, loquacious.

Source: Oxford Dictionary