Saying Thursday in Spanish is quite simple. The most common way to say it is “jueves.” This word comes from the Latin root “dies Iovis,” which translates to English as “Jove’s Day.” Jove was another name for Jupiter, one of the main gods in Roman mythology. In some parts of Spain and Latin America, Thursday may be referred to as “viernes” instead of jueves due to a local dialect. Viernes literally means Friday, however it is used colloquially when referring to Thursdays.
As with any language though, there are variations depending on where you are located so it’s best not to assume that everyone will understand either term without clarification. When speaking about a specific date or event that occurs on a Thursday, you can use phrases such as “el jueves” (the Thursday) or “este jueves” (this Thursday). If you want to refer generally about activities occurring on Thursdays you can say something like: los jueves (on Thursdays), cada semana los jueves (every week on Thursdays), o cada mes el tercer día de la semana es un juevees (every month the third day of the week is a Thursday).
The phrase for Good Thursday would be “Buen Jueves” while Happy Thursday would be translated as “Feliz Jueves!” It should also be noted that if someone says they have plans this weekend but don’t mention what day they plan on doing them then it could mean either Friday or Saturday since these two days usually make up weekends in many countries around the world including Spain and Latin America.