Y2K

American  

[wahy-too-key] / ˈwaɪˌtuˈkeɪ /

abbreviation

1. the year 2000.

2. Also called Y2K bug.  Also called millennium bug.  Also called Y2K problem,.  a bug that could cause computers or software to misinterpret a year after 1999 as having the first two digits 19 instead of 20, due to the coding of dates using only the last two digits of the four-digit year.

---

adjective

1. relating to or characteristic of the late 1990s and early 2000s.

   The outfit merges Y2K aesthetics with contemporary trends.

Y2K British  

noun

1. another name for the year 2000 _ad (esp referring to the millennium bug)

---

Etymology

Origin of Y2K

First recorded in 1995–2000; Y(ear) + 2 + K symbol for the number 1000

Example Sentences

Licensing for movies and TV is also booming, and with Y2K nostalgia permeating today’s media, Spears may be selling at an opportune time.

From Los Angeles Times • Feb. 10, 2026

Yet while Gap may never be able to reclaim its Y2K heyday, the shares are staging a comeback, up double-digits so far in 2025—although up more modestly since Barron’s recommended them in early December 2024.

From Barron's • Dec. 3, 2025

Young people thrifting clothes as they embrace their Y2K or cottagecore aesthetics have helped secondhand shopping shed its stigma, turning it into a trend, not a necessity.

From MarketWatch • Nov. 19, 2025

Indeed, Y2K dress-up days are popping up in workplaces and on college campuses.

From The Wall Street Journal • Oct. 16, 2025

I should have forced him to tell me about Y2K.

From "The First State of Being" by Erin Entrada Kelly