How many letters does the top answer for “a person of nearly the same age as another” have?

The most common answer is coeval (6 letters).

Crossword clue: a person of nearly the same age as another

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

coeval 6 letters wn-def

a person of nearly the same age as another

contemporary 12 letters wn-def

a person of nearly the same age as another

a person with the same name as another 50% similar → namesake