taciturn

adjectives

habitually reserved and uncommunicative
taciturn
is derived from
taciturnity
antonym
voluble
is similar to
(British colloquial) not inclined to conversation
buttoned-up
is similar to
temperamentally disinclined to talk
reticent, untalkative
see also
not inclined to talk or give information or express opinions
incommunicative, uncommunicative
see also
expressing much in few words
"a concise explanation"
concise