Definition of "millennial"
millennial
adjective
not comparable
(by extension, originally US, demography) Often capitalized: of or relating to, or characteristic of, people born in the last two decades of the 20th century from around the early 1980s to the mid 1990s (with 1996 births cited as the last Millennial year), and who reached adulthood early in the third millennium C.E.
noun
plural millennials
(originally US, demography) Often capitalized: a person from the generation born in the last two decades of the 20th century, from around the early 1980s to the mid-1990s and who reached adulthood early in the third millennium C.E., characterized by their familiarity with computer technology and poorer financial prospects than their parents.
(obsolete, rare) A thousandth anniversary; also, a celebration of such an anniversary.