How many letters does the top answer for “a dazzling luster or brilliancy.” have?

The most common answer is glariness (9 letters).

Crossword clue: a dazzling luster or brilliancy.

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

glariness 9 letters web-def

A dazzling luster or brilliancy.

glaringness 11 letters web-def

A dazzling luster or brilliancy.

a light of dazzling brilliancy. 50% similar → dazzle