An interjection is a word or expression used to convey emotions, reactions, or spontaneous feelings, often standing alone in speech. Historically, it has been categorized in various ways, from Greek adverbs to Latin-independent parts of speech, reflecting its complex role in language. Authors like Percival Leigh noted its status as one of English’s nine parts of speech, while F.
Max Müller likened involuntary sounds to interjections, emphasizing their emotive spontaneity. Across cultures and grammatical systems, interjections connect syntax and expression, functioning as deictic markers of context-specific emotions. Their variety—ranging from exclamations and curses to social signals—reveals a universal yet multifaceted linguistic phenomenon.