The most respectful and accurate terms to use are:
* Roma - referring to the Roma people, who have a distinct culture and language.
* Romany - another term used by the Roma people themselves.
* Romani - the singular form of "Roma".
* Traveller - a broader term referring to various groups of people who travel and have nomadic lifestyles.
It's important to remember that using these terms respectfully depends on context and the individual's preference. It's always best to ask someone how they would like to be referred to.