| December 4 | December 3 | December 2 |
| December 1December 1 is the 335th (in leap years the 336th) day of the year in the Gregorian calendar. There are 30 days remaining. Events 1640 Portugal regains its independence from Spain and John IV of Portugal becomes king. 1822 Peter I is crowned as Emperor of | December 23December 23 is the 357th day of the year in the Gregorian Calendar (358th in leap years). There are 8 days remaining. Events 619 Boniface V becomes Pope 1620 Construction of Plymouth Colony begins 1823 A Visit From St. Nicholas attributed to Clement Clark | December 24December 24 is the 358th day of the year in the Gregorian Calendar (359th in leap years). There are 7 days remaining. Events 640 John IV becomes Popel 1814 The Treaty of Ghent was signed which ended the War of 1812 1818 Silent Night composed by Franz Xave |
| December 26December 26 is the 360th day of the year in the Gregorian Calendar, 361st in leap years. There are 5 days remaining. Events 1400-1899 1481 Battle of Westbroek Holland defeats troops of Utrecht 1606 King Lear performed in the Court of England 1620 Elizabet | Definable numberA definable number is a real number which can be unambiguously defined by some mathematical statement. Formally, a real number a is called definable if there is some logical formula φ x in set theory which contains a single free variable x and such th | Depth of fieldIn film and photography, the depth of field is the distance in front of and behind the subject which appears to be in focus. For any given lens setting, there is only one distance at which a subject is in focus, but focus falls off gradually on either sid |
| Declaration of independenceA declaration of independence is a proclamation of the independence of a newly formed or reformed country from part or the whole of the territory of another, or a document containing such a declaration. Declarations of independence are generally made by o | DelocalisedIn chemical compounds, delocalised electrons do not belong strictly to a covalent bond or single atom, but move more freely between the parts of the compound. This stablizes the structure. One particular example is the benzene ring, where the central ring | December 11December 11 is the 345th day (346th in leap years) of the year in the Gregorian calendar. There are 20 days remaining. Events 1205 John Grey, Bishop of Norwich, elected Archbishop of Canterbury 1792 King Louis XVI of France goes on trial for treason 1816 |
| Decibel | Democratic Front for the Liberation of Palestine | Density |
| Developmental biology | December 27 | Denaturation |
| Determinant | Delphinus (constellation) | Deus Ex |
| Deuterocanonical books | Denver, Colorado | Deuterium |
| Dead Sea | Depeche Mode | Devil |
| Dedham, Massachusetts | Deuteronomy | Design |
| Denormalization | Detroit Lions | Detroit Tigers |
| Deism | Democide | December 9 |
| Desmond Tutu | Declination | December 12 |
| Desmothoracid | Declension | Definition of religion |
| December 30 | Detroit, Michigan | Deccan Traps |
| Dewey Decimal Classification | December 10 | Delta-T |
| December 22 | Design pattern | Desi Arnaz |
| Destroyer | Debian GNU/Hurd | Dennis Hopper |
| Detroit Red Wings | Demiurge | Dehydroepiandrosterone |
| Deicide (band) | Democratic Progressive Party | Derived group |
| December 19 | December 20 | December 21 |
| December 14 | December 13 | Delaunay triangulation |
| Defendant | Denis Auguste Affre | Denis Leary |
| Dextromethorphan | Deconstruction | Déjà vu |
| December 29 | Despina | Deque |
| Dean R. Koontz | Deimos | Delaware corporation |
| Detroit River | Derek Walcott | Decipherment |
| Decca Navigation System | Defense Advanced Research Projects Agency | Deprogramming |
| Devanagari | DEC Alpha | Defense |
| Death of a Hero | Degree Confluence Project | Debit card |
| Dewar flask | Developmental psychology | Della Thelma Duck |
| Derry | Despotism | Deep Space 1 |
| Design Science License | De Havilland Mosquito | Device driver |
| Defense Distinguished Service Medal | Devo | Dean Kamen |
| Derivative security | De jure | Des Moines, Iowa |
