Roman numeral in the context of "1st century"

The 1st century was the century spanning AD 1 (represented by the Roman numeral I) through AD 100 (C) according to the Julian calendar. It is often written as the 1st century AD or 1st century CE to distinguish it from the 1st century BC (or BCE) which preceded it. The 1st century is considered part of the Classical era, epoch, or historical period. The Roman Empire, Han China and the Parthian Persia were the most powerful and hegemonic states.

During this century, the Roman Empire (ruled by the Julio-Claudian and Flavian dynasties) continued to be in a period of relative stability known as Pax Romana, withstanding a financial crisis in 33 and a civil war in 69. In Europe, Rome expanded into Britain and fought wars in Germania and Dacia. In Africa, Rome was challenged by Tacfarinas, who led his own Musulamii tribe and a loose and changing coalition of other Berber tribes before being defeated in 24. In West Asia, Rome defeated a Jewish rebellion (66–73) and fought a war with Parthia from 58–63, though the latter conflict was inconclusive. In East Asia, the Chinese Western Han dynasty was overthrown and replaced by the Xin dynasty in 9, which in turn faced its own rebel movements (namely the Red Eyebrows and Lulin), and was replaced by the Eastern Han dynasty in 25. The Eastern Han dynasty then faced and quelled a rebellion by the Trưng sisters (40–43). In 58, the Eastern Han dynasty entered a golden age with the Rule of Ming and Zhang, who were generally regarded as able administrators who cared about the common welfare of the people and who promoted officials with integrity. On its northern frontier, the Chinese dynasties waged intermittent war with the Xiongnu before emerging victorious in 91. The states of Funan and Xianbei were also established in this century.

A regnal name, regnant name, or reign name is the name used by monarchs and popes during their reigns and subsequently, historically. Since ancient times, some monarchs have chosen to use a different name from their original name when they accede to the monarchy.

The regnal name is usually followed by a regnal number, written as a Roman numeral, to differentiate that monarch from others who have used the same name while ruling the same realm. In some cases, the monarch has more than one regnal name, but the regnal number is based on only one of those names, for example Charles X Gustav of Sweden. If a monarch reigns in more than one realm, they may carry different ordinals in each one, as some realms may have had different numbers of rulers of the same regnal name. For example, the same person was both King James VI of Scotland and King James I of England.

Variations in pressure and temperature give rise to different phases of ice, which have varying properties and molecular geometries. Currently, twenty-two crystalline phases have been observed, including ice I_h, I_c, ..., XXI. In modern history, phases have been discovered through scientific research with various techniques including pressurization, force application, nucleation agents, and others.

On Earth, most ice is found in the hexagonal Ice I_h phase. Less common phases may be found in the atmosphere and underground due to more extreme pressures and temperatures. Some phases are manufactured for nano scale uses due to their properties. In space, amorphous ice is the most common form as confirmed by observation. Thus, it is theorized to be the most common phase in the universe. Various other phases could be found naturally in astronomical objects.

An overline, overscore, or overbar, is a typographical feature of a horizontal line drawn immediately above the text. In old mathematical notation, an overline was called a vinculum, a notation for grouping symbols which is expressed in modern notation by parentheses, though it persists for symbols under a radical sign. The original use in Ancient Greek was to indicate compositions of Greek letters as Greek numerals. In Latin, it indicates Roman numerals multiplied by a thousand and it forms medieval abbreviations (sigla). Marking one or more words with a continuous line above the characters is sometimes called overstriking, though overstriking generally refers to printing one character on top of an already-printed character.

An overline, that is, a single line above a chunk of text, should not be confused with the macron, a diacritical mark placed above (or sometimes below) individual letters. The macron is narrower than the character box.

In music theory, Roman numeral analysis is a type of harmonic analysis in which chords are represented by Roman numerals, which encode the chord's degree and harmonic function within a given musical key.

Specific notation conventions vary: some theorists use uppercase numerals (e.g. I, IV, V) to represent major chords, and lowercase numerals (e.g. ii, iii, vi) to represent minor chords. Others use uppercase numerals for all chords regardless of their quality. (As the II, III, and VI chords always are minor chords and the VII always diminished, a further distinguishment is thought unneeded, see table for Major Diatonic scale below)

The Principality of Reuss-Gera (German: Fürstentum Reuß-Gera), officially called the Principality of Reuss Junior Line (German: Fürstentum Reuß jüngerer Linie) after 1848, was a sovereign state in modern Germany, ruled by members of the House of Reuss. It was one of the successor states of the Imperial County of Reuss. The Counts Reuss, with their respective capitals and Residenzen at Gera, Schleiz, Lobenstein, Köstritz and Ebersdorf, were all elevated to the title of prince (Fürst) in 1806. Their successor branch heads shared that title, while their cadets were also each titled prince (Prinz). Thus all males of the family were properly "Prince Heinrich (Roman numeral) Reuss, J.L.", without use of a nobiliary particle, although for convenience their branch names remained in colloquial use (for example, "Prince Heinrich I Reuss of Köstritz").

Group 12, by modern IUPAC numbering, is a group of chemical elements in the periodic table. It includes zinc (Zn), cadmium (Cd), mercury (Hg), and copernicium (Cn). Formerly this group was named IIB (pronounced as "group two B", as the "II" is a Roman numeral) by CAS and old IUPAC system.

The three group 12 elements that occur naturally are zinc, cadmium and mercury. They are all widely used in electric and electronic applications, as well as in various alloys. The first two members of the group share similar properties as they are solid metals under standard conditions. Mercury is the only metal that is known to be a liquid at room temperature – as copernicium's boiling point has not yet been measured accurately enough, it is not yet known whether it is a liquid or a gas under standard conditions. While zinc is very important in the biochemistry of living organisms, cadmium and mercury are both highly toxic. As copernicium does not occur in nature, it has to be synthesized in the laboratory.