Similar words
apelido
apelido is the everyday common word for "nickname"; alcunha is more formal or literary, sometimes with a mocking or uncomplimentary connotation.
Similar in other languages
Spanish
sobrenombre
sobrenombre is the Spanish word for the same thing — both mean "nickname."
French
surnom
surnom is the French word for the same thing — both mean "nickname."
Practice
1 What does alcunha mean?
nickname
2 Fill the gap: Tinha uma ___.
Full sentence: Tinha uma alcunha. (He had a nickname.)
3 Which fingerprint chart matches alcunha?
alcunha: neutral register, common frequency, general domain, neutral connotation.