Casual. Corporate casual. Business casual. Smart casual. Resort casual. Don't leave meeting attendees baffled about your event's dress code.
Explain what you mean by "business casual" or "corporate casual," etc. with examples of appropriate attire for men and women. One event's "resort casual" encouraged wearing jeans, while another explained that shorts were acceptable, but not denim or cutoffs.
Strike the right tone in offering your advice to attendees, whether it's a formal "suits are not appropriate" or a friendly "leave your ties at home!"
If you or your boss will attend a meeting where the dress code is unclear, conduct casual research: Contact someone in the host organization, talk with previous attendees to learn what people really wear (ties are encouraged, but no one wears one) or seek the advice of experts at a clothing shop that caters to businesspeople.