THE holiday season brings many challenges, from the practical (what to give your boss) to the emotional (what to give your boss that will kill him in his sleep).

Yes, the proper Christmas spirit can be difficult to get right — much less display — especially when trying to figure out how to dress for the gantlet of holiday parties if, as is often the case, you have to go to one directly from work.

This particular quandary has intensified with the advent of a new directive, increasingly common on invitations, urging festive attire. It’s not black tie, it’s not business dress, and it’s definitely not come as you are. But what is “festive,” exactly?

“It doesn’t mean anything,” said Jennifer Gilbert, the founder of Save the Date, a New York special events company. “That’s the whole problem. So many people put that on invitations now, and no one really knows what it means. Well, women do. But 9 times out of 10, you say ‘festive attire’ and guys show up in a blazer, the shirt they wore to work, unbuttoned and without the tie, and jeans. So it ends up being the opposite of festive.”