queen mother

a queen dowager who is mother of a reigning sovereign.

Origin of queen mother

First recorded in 1570–80

The queen-mother found that she could not take these children with her, and so she ordered them all to be slain.

Genghis Khan, Makers of History Series |Jacob Abbott
After the two thousand had been dispersed162 or captured the "queen-mother" threw off the mask.

Castles and Chateaux of Old Touraine and the Loire Country |Francis Miltoun
"But so contemptible that the king can well despise it," replied the queen-mother.

Louise de la Valliere |Alexandre Dumas, Pere
If the meal was followed by any drinking, the queen-mother and the queen retired, before the concubines entered to play and sing.

The History of Antiquity |Max Duncker

And once on friendly terms again with the queen-mother, I may be dangerous toward some persons.

The Vicomte de Bragelonne |Alexandre Dumas

queen mother

the widow of a former king who is also the mother of the reigning sovereign