How many letters does the top answer for “a period marked by distinctive character or reckoned from a fixed point or event” have?

The most common answer is epoch (5 letters).

Crossword clue: a period marked by distinctive character or reckoned from a fixed point or event

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

epoch 5 letters wn-def

a period marked by distinctive character or reckoned from a fixed point or event

era 3 letters wn-def

a period marked by distinctive character or reckoned from a fixed point or event