Here are the possible solutions for diagonal rib of a vault clue
Answer
Clue
Relevancy
ogive
Clue
Diagonal rib of a vault
Rib of a Gothic vault
Definition
a pointed arch
serge
Clue
It has a diagonal rib
abe
Clue
Nickname of the man (born 2/12/1809) who gave the address at 18A, issued the 28A/45A, was the first elected president of the 60A Party, and whose name can be found in this puzzle's main diagonal
area
Clue
In a rhombus, half the product of its diagonal lengths