A 'dynasty' - pronounced with the stress on the first syllable, DINN-er-sti, IPA: /ˈdɪn əst ɪ/; in British RP the first vowel of this word (and the related words 'dynast' and 'dynastic') is the short '-i-' (IPA: /ɪ/), whereas American uses the diphthongal '-i-', /aɪ/ - is a succession of rulers who are all members of the same family - for example, the Tudor dynasty, which ruled England from 1485 to 1603: or the Saud dynasty, which has ruled the Kingdom of Saudi Arabia since 1932. The rulers who comprise a dynasty need not be kings or queens, but may be emperors or empresses, princes or princesses, counts or countesses, etc. A dynasty of this kind is sometimes referred to as a House (almost always with an initial capital letter) - for example, instead of 'the Tudor dynasty' we may speak of 'the House of Tudor'. (The word 'House' may be used to refer to any noble family, whether or not they were rulers.) Note that where X is the name of a dynasty, we must always say 'the X dynasty', not 'the dynasty of X', and 'the House of X', not 'the X House'.
The word 'dynasty' is also used to refer not to a succession of rulers from the same family but to any series of powerful leaders or influential figures who come from the same family, e.g., business tycoons, powerful industrialists, or influential figures in politics. Examples are the Krupp dynasty, the German family of steel and armaments manufacturers which included Alfred Krupp (1812-1887), his son Friedrich Alfred Krupp (1854-1902), and Friedrich Alfred's son-in-law Gustav Krupp von Bohlen und Halbach (1870-1950); and the Kennedy dynasty, the family of Joseph Patrick Kennedy Sr. (1888-1969), which has been prominent in American political life and has included the brothers John Fitzgerald Kennedy (1917-1963, U.S. President 1960-1963) ('JFK'), Robert Francis ('Bobby') Kennedy (1925-1968), and Edward Moore ('Teddy') Kennedy (1932-). A dynasty of this kind may not be referred to as a 'House'.
The word 'dynasty' comes, through Late Latin, from the Greek δυναστεία (dunasteia), which means 'power or domination', and comes from the verb δύναμαι, dunamai, I am able, am strong enough (to do). The participial phrase οἱ δυνάμενοι, hoi dunamenoi, 'those who are able or strong', was regularly used to refer to the men of power, rank, and influence in a state. The word δυναστεία (dunasteia) was also sometimes used to characterise a particular type of political constitution, i.e., rule by a narrow oligarchy, by contrast with a more democratic constitution (ἰσονομία, isonomia) - see, e.g., Thucydides, History of the Peloponnesian War, 4, 78).
A member of a dynasty is a dynast - pronounced with the stress on the first syllable, which has a short '-i-' (/ˈdɪn ə (or æ)st/). The adjective from 'dynasty' is 'dynastic' - pronounced with the stress on the second syllable (/dɪn ˈæst ɪk/).
- 'Dynasty' is also the title of an American television soap opera which ran for eight years in the 1980s and centred around the fortunes of the Carringtons, a wealthy oil family who lived in Denver, Colorado.
- The Dynasts is an 'epic drama' in verse by Thomas Hardy (1840-1928) about the Napoleonic wars, "in three parts, nineteen acts and one hundred and thirty scenes". The three parts were published in 1904, 1906 and 1908. Hardy regarded it as his masterpiece, but there have been few who have agreed. Its huge scale may make it more suitable for radio than the theatre. In 1914-15, Harley Granville-Barker put on a successful three-hour production of some 30 scenes of The Dynasts, at the Kingsway Theatre, London, and it has been broadcast on BBC radio.
You may also care to see AWE's account of Roman Imperial Dynasties.