The name Thais means The Bond and is of Greek origin. Thais is a name that's been used primarily by parents who are considering baby names for girls.
THAÏS is the title of a novel by Anatole France, made into an opera by Jules Massenet. It was based on a 4th century saint from Alexandria.
Could be pronounced "Ties," "Tha-EES" or "THY-ess" depending on the geographical context. In Greek it would be closest to "Tha-EES" with the TH pronounced as in "bath."