What does "dead ringer" mean?

Someone or something that very closely resembles another; someone or something easily mistaken for another.

What is a synonym for "dead ringer"?

Common synonyms include: actual thing, carbon copy, clone, companion, copy, ditto.

noun

noun ·Uncommon ·Advanced level

Noun

1
Someone or something that very closely resembles another; someone or something easily mistaken for another. idiomatic
"He is a dead ringer for his grandfather at that age."
2
a person who is almost identical to another wordnet

"He is a dead ringer for his grandfather at that age."

See ringer (“substitute”) and ring the changes