From The Collaborative International Dictionary of English v.0.48 :
buttoned \buttoned\ adj.
furnished with buttons or something buttonlike. Opposite of
unbuttoned. [Narrower terms: botonee, botonnee;
button-down; closed]
[WordNet 1.5]
From WordNet (r) 3.0 (2006) :
button-down
adj 1: unimaginatively conventional; "a colorful character in
the buttoned-down, dull-grey world of business"- Newsweek
[syn: button-down, buttoned-down, conservative]
2: of a shirt; having the ends of the collar fastened down by
buttons; "Brooks Brothers button-down shirts"