From the MENS WAREHOUSE website..
Question What do the terms Dress Casual or business casual mean?
Answer Whether it's referred to as Dress Casual or business casual, the recent dressing down on the American workplace has proven to be more confusing than liberating. You are not alone in your uncertainty. Men's Wearhouse offers a free video, called Casual Know-How, that addresses many of the questions you may have. You can order it over the website or by calling 1-877-986-9669. The click path on the website is as follows: Homepage, Our Advantages, Free Dress Casual Video.
Many men hear the word "casual" and think that they may wear chinos and a tee shirt to the office. Do not make this mistake. There are basic elements of a Dress Casual wardrobe, many of which you may already have in your closet. Tailored wool or microfiber slacks (yes, tailored) are essential. You can replace your point collar dress shirts and ties with fine gauge knit tops, such as merino wool polos or silk/cotton mock turtle necks. Fine gauge knits can stand alone in a casual office or be worn under a sport coat in more conservative settings or when meeting with clients. Shoes should have leather uppers and either lugged or leather soles. Popular styles are monk strap and cap toe. Belts should always be leather and match your shoe color. Finally, you can still wear your suit. Simply replace your shirt and tie with a silk mock neck for a casual look that commands respect. There are, of course, other options. For more details, check out the Casual Know-How feature article in Guy'dlines, or talk with a wardrobe consultant at the Men's Wearhouse near you.