Adjectives are one of the English parts of speech, although historically they were classed together with the nouns. Certain words that were traditionally considered to be adjectives, including the, this, my, etc., are today usually classed separately, as determiners.
Adjective comes from Latin (nōmen) adjectīvum "additional (noun)", a calque of Ancient Greek: ἐπίθετον (ὄνομα), translit. epítheton (ónoma), lit. 'additional (noun)'. In the grammatical tradition of Latin and Greek, because adjectives were inflected for gender, number, and case like nouns (a process called declension), they were considered a subtype of noun. The words that are today typically called nouns were then called substantive nouns (nōmen substantīvum). The terms noun substantive and noun adjective were formerly used in English, but the terms are now obsolete.
A given occurrence of an adjective can generally be classified into one of three kinds of use:
Adjectives feature as a part of speech (word class) in most languages. In some languages, the words that serve the semantic function of adjectives are categorized together with some other class, such as nouns or verbs. In the phrase "a Ford car", "Ford" is unquestionably a noun, but its function is adjectival: to modify "car". In some languages adjectives can function as nouns: "un rojo", "a red (object)" (Span.). As for "confusion" with verbs, rather than an adjective meaning "big", a language might have a verb that means "to be big", and could then use an attributive verb construction analogous to "big-being house" to express what English expresses as "big house". Such an analysis is possible for the grammar of Standard Chinese, for example.
Different languages do not always use adjectives in exactly the same situations. For example, where English uses to be hungry (hungry being an adjective), Dutch, French, and Spanish use honger hebben, avoir faim, and tener hambre respectively (literally "to have hunger", the words for "hunger" being nouns). Similarly, where Hebrew uses the adjective זקוק zaqūq (roughly "in need of"), English uses the verb "to need".