What is the meaning of Passaggio?

The transition area between a singer's vocal registers.

A type of musical ornamentation or embellishment, common in the late 16th and early 17th century, that uses diminutions to fill in or connect between melodic notes.

passage, passing, gap

transfer, transition

route

traffic

pass

aisle

transit

phase, stage, period, level, degree, step

Source: wiktionary.org