both

The English word "both," used to refer collectively to two people or things, traces its origins deep‌​‌​‍​‌​‌​‍​‍​‍​‍​‌​‌​‍​‌​‍​‍​‍​‌​‌​‍​‌​‍​‍​‌​‍​‌​‍​‍​‌​‌​‌​‌​‌ into the history of the Indo-European language family, preserving a linguistic feature largely lost in most modern languages: the dual number. This grammatical category, distinct from singular and plural, specifically marked pairs and was once a living and productive element in many ancient Indo-European tongues.

In Old English, the concept of "both" was expressed by the forms bā and bēgen. These forms were not mere synonyms but reflected a gender distinction: bēgen was masculine, while bā was used for feminine and neuter. This gender agreement aligns with the broader Indo-European system, where adjectives and pronouns typically inflected to match the gender of the nouns they modified. The Old English forms themselves derive from the Proto-Germanic root *baiz, which is reconstructed to have meant "both." This root, in turn, is believed to stem from the Proto-Indo-European (PIE) root *bʰoh₂ or *bʰóh₁, a term signifying "both" in an emphatic dual form. This PIE root is related to *dwóh₁, the numeral "two," underscoring the close conceptual and morphological link between the number two and the dual grammatical category.

The dual number was a robust grammatical feature in early Indo-European languages, preserved in classical languages such as Sanskrit, Ancient Greek, and Old Church Slavonic, as well as in Gothic, an East Germanic language. In these languages, the dual was used to mark exactly two entities, distinct from singular (one) and plural (more than two). English, like most modern Indo-European languages, has lost the dual as a productive grammatical category, but "both" remains a fossilized remnant of this system. Its original function was to agree in gender and number with the nouns it referred to, a feature that has largely disappeared in contemporary English usage.

The Old Norse language, spoken by the Scandinavian settlers who colonized parts of England during the Viking Age, contributed significantly to the development of Middle English vocabulary. Among the Norse borrowings was the form bāðir, meaning "both." This Old Norse term is a cognate of the Old English bā and bēgen, all descending from the same Proto-Germanic and ultimately PIE roots. The Norse influence on English during the Danelaw period, roughly spanning the 9th to 11th centuries, was profound and far-reaching. It reshaped many fundamental English words, including pronouns such as they, them, and their, as well as verbs like take, get, and give. The Norse form bāðir either reinforced or replaced the Old English forms in Middle English, contributing to the survival and evolution of "both" in the English lexicon.

Cognates of "both" are found across the Germanic and Baltic branches of the Indo-European family. Old High German had bēde, which survives in modern German as beide, carrying the same meaning. Gothic, an East Germanic language, used bai for "both." In the Baltic languages, Lithuanian preserves abù, meaning "both," and in Sanskrit, the classical Indo-Aryan language, the form ubháu serves the same function. These cognates collectively attest to the antiquity and widespread nature of the dual concept in Indo-European languages.

The survival of "both" in English as a word specifically denoting two entities regarded together is thus a linguistic fossil, a trace of a once-common grammatical category that has otherwise vanished from English and most other modern Indo-European languages. While the dual number has disappeared from English grammar, the word "both" continues to function as a vestige of this system, preserving a semantic and morphological link to a distant linguistic past. Its history illustrates the complex interplay of inheritance and borrowing that characterizes the English language, shaped by its Germanic roots and the substantial Norse influence during the early medieval period.

"both" originates from the Old English bā and bēgen, themselves derived from Proto-Germanic *baiz and ultimately from the Proto-Indo-European root *bʰoh₂ or *bʰóh₁, meaning "both." The word was reinforced or replaced in Middle English by the Old Norse bāðir, reflecting the extensive Norse impact on English vocabulary during the Viking Age. Its cognates across Germanic and Indo-Aryan languages highlight the once-common dual number in Indo-European, a grammatical category now largely lost but preserved in English through this enduring term.