Longman Dictionary of Contemporary English
The Collaborative International Dictionary
buttoned-up \buttoned-up\ adj.
taciturn. Opposite of voluble. [British colloquial]
conservative in professional manner; as, employers are looking for buttoned-up types.
Wiktionary
a. 1 conservative. 2 Carefully planned and executed.
WordNet
adj. (British colloquial) not inclined to conversation
conservative in professional manner; "employers are looking for buttoned-up types"
Usage examples of "buttoned-up".
Bayonets appear, and in the midst of the bayonets a man in a buttoned-up overcoat, with a tricolored sash upon his coat.
As he gave me that slowly devouring look of his, while twisting up the strings of his bag before he hastened with it after Mr. Kenge, the benignant shadow of whose conversational presence he seemed afraid to leave, he gave one gasp as if he had swallowed the last morsel of his client, and his black buttoned-up unwholesome figure glided away to the low door at the end of the Hall.
In my buttoned-up chef's coat, check pants, neckerchief and standard-issue leatherette knife roll-up, I arrived determined but full of attitude.