Origins
The word 'lexicon' arrived in English around 1603, borrowed from Greek 'lexikon biblion' — literally 'word-book.' It was the neuter form of 'lexikos' (of or pertaining to words), derived from 'lexis' (word, speech, diction), which came from the verb 'legein' (to say, to speak, to gather). And it is in that verb that the etymology grows truly interesting, because 'legein' carries two seemingly unrelated meanings — to speak and to gather — that reveal a profound ancient insight about what language actually is.
The Proto-Indo-European root behind 'legein' is *leg-, meaning 'to collect, to gather.' The same root produced Latin 'legere,' which also meant both 'to gather' and 'to read.' Roman farmers 'legebant' olives (gathered them); Roman scholars 'legebant' books (read them). The connection is not accidental. Reading, in the ancient world, was conceived as gathering — collecting meanings from marks on a surface, assembling sense from scattered signs. And speaking was similarly conceived as a gathering of words into organized utterance. A lexicon, then, is not merely a list of words but a gathering place, a harvest of language.
The PIE root *leg- has been spectacularly productive across the Indo-European family. From its Latin branch, through 'legere,' come 'lecture' (a reading), 'legend' (something to be read), 'legible,' 'lesson' (from Latin 'lectio,' a reading), 'collect' (to gather together), 'select' (to gather apart), 'elect' (to gather out), 'elegant' (originally 'choosing well'), 'intelligent' (reading between), 'neglect' (not gathering, not picking up), and 'diligent' (choosing earnestly). From the Greek branch come 'logic' (the art of reasoned speech), 'logos' (word, reason, principle — one of the most consequential words in Western philosophy and theology), 'dialogue,' 'catalogue' (a counting-down of a list), 'epilogue,' 'prologue,' and 'lexicon' itself.
Latin Roots
The Greek word 'lexikon' first referred specifically to dictionaries of Greek, Hebrew, or Arabic — the learned languages of European scholarship. English dictionaries were typically called 'dictionaries' (from Latin 'dictio,' a saying), while 'lexicon' retained an aura of classical erudition. Over time, this distinction softened. By the 19th century, 'lexicon' could refer to any dictionary, and it had also acquired its more abstract meaning: the total vocabulary of a language, a person, or a field of knowledge. We speak of Shakespeare's lexicon (his working vocabulary of roughly 31,000 distinct words), the medical lexicon, or the lexicon of a three-year-old child.
In modern linguistics, the lexicon has become a central theoretical concept. It is the mental dictionary that every speaker carries — not just a list of words and their meanings, but a structured network of phonological, syntactic, and semantic information. When you know a word, you know far more than its definition: you know its pronunciation, its grammatical category, the constructions it fits into, its connotations, its register (formal or informal), and its relationships to other words. The mental lexicon is one of the most complex data structures in nature, containing tens of thousands of entries that can be accessed in a fraction of a second.
The study of the lexicon — lexicology — and the practice of recording it — lexicography — have evolved dramatically since the first Greek word-lists. Samuel Johnson's Dictionary of 1755 and the Oxford English Dictionary (begun in 1857, first completed in 1928) represent heroic attempts to gather the full lexicon of English into a single work. The OED currently contains over 600,000 entries. Yet even this vast collection is only a partial gathering — new words enter the lexicon constantly, old words shift in meaning, and the total vocabulary of English, if slang, technical terminology, and regional dialects are included, may exceed a million items.
Greek Origins
The word 'lexicon,' born from the Greek idea that language is a gathering, remains the most elegant name for this extraordinary collection. Every human being carries one, assembled over a lifetime of listening, reading, and speaking — a personal harvest of words gathered from the vast field of language.