A dress code is a compression of information the host assumes you already have. That works at an annual event where the guests repeat. It fails the first time you attend, and it fails hardest with the codes that sound like they are giving you freedom.
Black tie
The least ambiguous of them. A dinner jacket, or a floor-length or formal cocktail-length dress. In London and Tokyo this is read literally and the door will notice a lounge suit. In Los Angeles it is read as a strong suggestion.
Creative black tie
This asks for black tie with one deliberate departure. A coloured jacket, an unexpected fabric, a strong shoe. One departure, not three. The common failure is treating the word creative as permission to abandon the formality entirely, which reads as having misread the invitation rather than having interpreted it.
Cocktail
A suit, or a shorter dress. The trap is the venue rather than the words: cocktail at a private residence and cocktail in a hotel ballroom want different levels of formality, and the invitation will not tell you which you are getting. Look at the address.
Smart casual
Almost always means a jacket, and almost never means jeans, whatever the phrase suggests. In Singapore this code will turn away open shoes. In Sydney it will not. Assume the stricter reading if you have not been to the venue.
Lounge suit and business formal
A regular suit and tie. These appear on corporate invitations and mean roughly what you would wear to a client meeting, with better shoes.
What to do with a code you cannot place
- Send us the invitation itself rather than a description of it. The code, the venue, and the timing are usually all printed on it
- Check whether the ticket names an enclosure or a box. Those often carry their own rules
- Ask what last year looked like. Recurring events are the easiest to dress for once somebody has described one
- When two readings are possible, take the more formal one. Being slightly overdressed is invisible
Your companion will dress to whatever the invitation says, and will ask if it says something that could go two ways. Sending the invitation through at the booking stage removes an entire category of evening-of problems.