HJ may refer to:

Science, technology, and mathematics

Hall–Janko group In the area of modern algebra known as group theory, the Janko group ''J2'' or the Hall-Janko group ''HJ'' is a sporadic simple group of Order (group theory), order : 604,800 = 2733527 : ≈ 6. History and properties ''J2'' i ...

, a mathematical group *

Hamilton–Jacobi equation In physics, the Hamilton–Jacobi equation, named after William Rowan Hamilton and Carl Gustav Jacob Jacobi, is an alternative formulation of classical mechanics, equivalent to other formulations such as Newton's laws of motion, Lagrangian mecha ...

, an equation in classical mechanics which also has relations to quantum physics * U.S. code for a cryptographic key change; see cryptoperiod

Other uses

* , a two-letter combination used in some languages * hj-reduction in English, dropping the sound before *

Hajji Hajji (; sometimes spelled Hajjeh, Hadji, Haji, Alhaji, Al-Hadj, Al-Haj or El-Hajj) is an honorific title which is given to a Muslim who has successfully completed the Hajj to Mecca. Etymology ''Hajji'' is derived from the Arabic ' (), which i ...

(Hj.), an Islamic honorific *

Handjob A handjob (also spelled hand job) is a manual sex act involving a person stimulating the penis or scrotum of another by using the hand. This is done to induce an erection for sexual pleasure, sexual arousal and may result in orgasm and ejaculat ...

* ''hic jacet'' ('here lies'),

Latin phrase This is a list of Wikipedia articles of Latin phrases and their translation into English. To view all phrases on a single, lengthy document, see: List of Latin phrases (full). Lists of pages * List of Latin phrases (A) * List of Latin phrases ( ...

on gravestones * Hilal-i-Jurat, post-nominal for Pakistan honour * Hitler-Jugend (Hitler Youth) * Holden HJ, an Australian car 1974-1976 *

Hot Jupiter Hot Jupiters (sometimes called hot Saturns) are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter (i.e. Jupiter analogue, Jupiter analogues) but that have very short orbital periods (). The close proximity to t ...

, a type of planet *

Tasman Cargo Airlines Tasman Cargo Airlines Pty. Limited is an Australian cargo airline with the head office in Sydney, Australia. It operates scheduled international cargo services on behalf of DHL Express, DHL and ad hoc domestic and international cargo charters. ...

, IATA airline designator * '' Jiaguwen Heji'', the standard comprehensive collection of rubbings of ancient Chinese oracle bone inscriptions * "High jump" athletics abbreviation in track and field {{disambiguation