It is an abstract noun because it is not something you can touch.
Parts of speech
Abstract and concrete are classifications that denote whether a term describes an object with a physical referent or one with no physical referents. They are most commonly used in philosophy and semantics. Abstract objects are sometimes called abstracta (sing. abstractum) and concrete objects are sometimes called concreta (sing. concretum). An abstract object is an object which does not exist at any particular time or place, but rather exists as a type of thing, i.e. an idea, or abstraction. The term 'abstract object' is said to have been coined by Willard Van Orman Quine. The study of abstract objects is called abstract object theory.
The type-token distinction identifies physical objects that are tokens of a particular type of thing. The "type" that it is a part of, is in itself an abstract object. The abstract-concrete distinction is often introduced and initially understood in terms of paradigmatic examples of objects of each kind:
In grammar, a part of speech (also a word class, a lexical class, or a lexical category) is a linguistic category of words (or more precisely lexical items), which is generally defined by the syntactic or morphological behaviour of the lexical item in question. Common linguistic categories include noun and verb, among others. There are open word classes, which constantly acquire new members, and closed word classes, which acquire new members infrequently if at all.
Almost all languages have the lexical categories noun and verb, but beyond these there are significant variations in different languages. For example, Japanese has as many as three classes of adjectives where English has one; Chinese, Korean and Japanese have nominal classifiers whereas European languages do not; many languages do not have a distinction between adjectives and adverbs, adjectives and verbs (see stative verbs) or adjectives and nouns]citation needed[, etc. This variation in the number of categories and their identifying properties entails that analysis be done for each individual language. Nevertheless the labels for each category are assigned on the basis of universal criteria.
A noun can co-occur with an article or an attributive adjective. Verbs and adjectives can't. In the following, an asterisk (*) in front of an example means that this example is ungrammatical.
Nouns are a part of speech typically denoting a person, place, thing, animal or idea. In linguistics, a noun is a member of a large, open lexical category whose members can occur as the main word in the subject of a clause, the object of a verb, or the object of a preposition.
Sultan (Arabic: سلطان Sulṭān, pronounced [ˈsulˈtˤɑːn]) is a noble title with several historical meanings. Originally, it was an Arabic language abstract noun meaning "strength", "authority", "rulership" and "dictatorship", derived from the masdar سلطة sulṭah, meaning "authority" or "power". Later, it came to be used as the title of certain rulers who claimed almost full sovereignty in practical terms (i.e., the lack of dependence on any higher ruler), without claiming the overall caliphate, or to refer to a powerful governor of a province within the caliphate.
The dynasty and lands ruled by a sultan are referred to as a sultanate (Arabic: سلطنة).