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Double Ninth Festival (重阳节)

Double Ninth Festival (重阳节, Chongyang jie, also Chongjiu, Climbing Heights Festival, Seniors' Festival): Chinese festival on the 9th day of the 9th lunar month, marked by climbing heights, chrysanthemum wine, dogwood, and Chongyang cake; a statutory Seniors' Festival since 2012 and national intangible cultural heritage since 2006.

Double Occupancy

Double Occupancy (டபுள் ஆக்யுபன்சி) is a 2026 Tamil fantasy romantic comedy directed by debutant Aswin Kandasamy, starring Santhosh and Reshma Venkatesh as Rajini, a man by night and woman by day, released 12 June 2026, certified UA 16+.

Double or Nothing (2020)

Double or Nothing (2020), produced by All Elite Wrestling on May 23, 2020, was a professional wrestling event that crowned new champions and hosted the first Stadium Stampede.

Double or Nothing (2021)

Double or Nothing (2021) was AEW's third Double or Nothing pay-per-view, held May 30, 2021 at Daily's Place, Jacksonville, before a full-capacity crowd of about 5,200; Omega retained, Baker won the women's title, and Inner Circle won Stadium Stampede II.

Double or Nothing (2022)

Double or Nothing (2022) was an AEW pay-per-view on May 29, 2022, at T-Mobile Arena in Paradise, Nevada, where CM Punk beat Hangman Adam Page for the AEW World Championship; Wardlow beat MJF and the Owen Hart Cup finals concluded there.

Double or Nothing (2023)

Double or Nothing (2023): AEW's fifth Double or Nothing pay-per-view, May 28, 2023, T-Mobile Arena, Paradise, Nevada. MJF retained the AEW World Title in the Four Pillars four-way; BCC won Anarchy in the Arena; 10,550 attendance, 130,000-135,000 buys.

Double or Nothing (2024)

Double or Nothing (2024) was an AEW pay-per-view event in Las Vegas on May 26, 2024. It featured MJF's return and the Anarchy in the Arena main event.

Double or Nothing (2025)

AEW Double or Nothing 2025, a pay-per-view held May 25, 2025 at Desert Diamond Arena, Glendale, Arizona; AEW's Arizona PPV debut. Adam Page and Mercedes Mone won Owen Hart Cup finals; Anarchy in the Arena returned.

Double or Nothing (2026)

Double or Nothing (2026) was AEW's May 24, 2026 pay-per-view at Louis Armstrong Stadium, Queens, New York, its first New York and HBO Max edition; MJF beat Darby Allin Title vs. Hair, Cage & Cope and Takeshita won titles.

Double outlet left ventricle

Double outlet left ventricle (DOLV) is a rare congenital heart defect in which the aorta and pulmonary artery both originate from the morphologic left ventricle, usually with a ventricular septal defect.

Double outlet right ventricle

Double outlet right ventricle (DORV), also called double-outlet right ventricle, is a congenital heart defect where both the aorta and pulmonary artery arise from the right ventricle, usually with a VSD; treated by biventricular repair, single-ventricle palliation, or palliation.

Double pendulum

The double pendulum is a pendulum with a second pendulum attached to its end, one of the simplest physical systems exhibiting deterministic chaos through strong sensitivity to initial conditions.

Double penetration

Double penetration (DP) is simultaneous penetration of one person in two orifices, usually vaginal and anal. Appears in 17-22% of some pornography samples; requires a new condom per act, ample water- or silicone-based lube, and never two condoms at once.

Double penetration dildo

A double penetration dildo, also called a double-ended dildo or double dildo, is a sex toy with insertable ends at both tips, usable solo or by two partners.

Double perovskite

A double perovskite is a crystal of formula A2BB′X6 whose single B cation site is split into two alternating sublattices, including lead-free halide optoelectronic materials.

Double planet

A double planet, also called a binary planet, is a pair of planet-sized bodies orbiting a shared barycenter outside the larger body, with no confirmed example known.

Double Q-learning

Double Q-learning is a reinforcement learning algorithm that uses two value estimators to remove the overestimation bias of Q-learning, introduced by Hado van Hasselt in 2010.

Double Qaimaqamate

The Double Qaimaqamate (القيامتيين في جبل لبنان) was the 1842 Ottoman partition of Mount Lebanon into a northern district under a Christian deputy governor and a southern one under a Druze deputy governor.

Double Rainbow (viral video)

Double Rainbow is a 2010 YouTube video of Paul "Bear" Vasquez (Hungrybear9562) weeping with joy at a double rainbow near Yosemite; viral after Jimmy Kimmel's July 2010 tweet, over 47 million views, Gregory Brothers auto-tune remix.

Double Ratchet Algorithm

The Double Ratchet Algorithm, also known as the Axolotl ratchet, is a key-management algorithm for end-to-end encrypted messaging that derives a fresh key for every message, securing Signal, WhatsApp, and Facebook Messenger.

Double Rayleigh scattering

Double Rayleigh scattering, also called double Rayleigh backscattering (DRB), is noise in optical fiber Raman amplifiers in which signal light backscattered twice returns as in-band crosstalk, limiting gain in long-haul systems.

Double resonance spectroscopy

Double resonance spectroscopy is a family of techniques in which two radiation fields, often at different wavelengths, drive two quantum transitions sharing a common level, revealing which lines in a congested spectrum belong together.

Double sampling (statistics)

Double sampling, also called two-phase sampling, is a survey sampling method that takes cheap auxiliary measurements on a large sample, then measures costly study variables on a subsample.

Double shield TBM

A double shield TBM (DS TBM) is a hard-rock tunnel boring machine combining an open gripper TBM and a single-shield TBM, switching thrust modes as ground conditions change.

Double solitaire

Double solitaire (double Klondike) is a two-player card game: each player runs an own 52-card Klondike tableau while both race to build shared foundations; most foundation cards wins.

Double Star (satellite)

Double Star (Tan Ce, "Explorer") was a joint China-ESA mission of two satellites, TC-1 and TC-2, launched in 2003 and 2004 to study Earth's magnetosphere with Cluster.

Double tap

Double tap, a firearms technique of two rapid shots at one target; also called hammer pair, contrasted with the controlled pair. Origin credited to Fairbairn and Sykes, 1930s Shanghai; splits .25-.35 s.

Double taxation

Double taxation, or dual taxation, arises when two or more States levy similar taxes on the same taxpayer, the same income, and the same period.

Double Team (film)

Double Team (1997) is a Tsui Hark action film starring Jean-Claude Van Damme, Dennis Rodman in his film debut, and Mickey Rourke; Columbia Pictures release about agent Jack Quinn rescuing his family from terrorist Stavros.

Double Teamed

Double Teamed is a 2002 Disney Channel Original Movie, premiered January 18, 2002, directed by Duwayne Dunham, dramatizing WNBA twins Heidi and Heather Burge's Palos Verdes High basketball years.