1. 
[syn: button-down, buttoned-down, conservative]
2.  of a shirt;  having the ends of the collar fastened down by buttons; 
- Example: "Brooks Brothers button-down shirts"
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]
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"