The Altar of Repose.
After that day,it is the good Friday which means the good day for Jesus.
Roman Catholic AnswerIt is known as Holy Thursday, or Maundy Thursday.
Thursday before Easter is known as Maundy Thursday in the Christian calendar.In some churches, it is also known as Holy Thursday. It is recognised as the day when Jesus administered the Eucharist to his apostles and washed their feet.
Roman Catholic AnswerThe Most Blessed Sacrament: after the Mass on Holy Thursday, which does not end with a blessing (as it is the start of the Triduum liturgy which continues on Good Friday), the priest gathers up all the consecrated Hosts, and instead of putting them in the Tabernacle carries them to the Altar of Repose. While carrying them, he covers them with a Humeral Veil. From the Altar of Repose they will retrieve Hosts to give Holy Communion on Good Friday, and to the sick and dying. For more on the altar of repose you may read responses from a professor of liturgy at a Pontifical University at the link below:
It would still be called a chapel unless if it is just an altar, then it would just be called an altar. A chapel is a holy room reserved for prayer and practising of faith only.
Other names for Holy Thursday are: Maundy Thursday Clean Thursday, Great Thursday, Green Thursday,Holy and Great Thursday, Red Thursday, Sharp Thursday, Sheer Thursday, Shrift Thursday, Thursday of the Mystical Supper.
From the way it sounds, it seems you are referring to the Altar.
There isn't really an "altar" in a mosque in the way that churches have one. There is a small recession in one wall, called a "mihrab" that indicates the direction to pray, and there is a platfrom that the imam sits on when giving a sermon, which is called a "mimbar," but no altar.
The Easter Triddum.
It can be called Palm Sunday or Passion Sunday.
In the Roman Catholic faith Holy Thursday is the first day of the Easter Triduum. Easter Triduum is the Holy Thursday, Good Friday, and Holy Saturday leading up to Easter. That entire week is called Holy Week which is not really regarded as a feast day. Feast days are usually reserved for specific saints.