- c. 500 BC
- Yāska, Nirukta The first treatise on etymology: every noun comes from a verb, and a name is explained by its sound and its sense together.
- 4th century BC
- Plato, Cratylus Socrates argues that letters imitate things — rho for motion, the breathy letters for shaking. The dialogue ends undecided, and the question it opened has never closed.
- c. 770
- al-Khalīl ibn Aḥmad, Kitāb al-ʿAyn The first dictionary of Arabic, ordered by where each sound is made in the throat, deepest first — and listing every permutation of a root’s consonants together, as one family.
- c. 1000
- Ibn Jinnī, al-Khaṣāʾiṣ The greater derivation: the permutations of a root share one meaning; and a chapter arguing that the sounds of words resemble what they mean.
- c. 1000
- Ibn Fāris, Maqāyīs al-Lugha Every Arabic root has a core sense from which all its words descend — the dictionary as a book of roots.
- 9th century
- Ibn al-Anbārī, Kitāb al-Aḍdād The catalogue of Arabic words that mean a thing and its opposite.
- 1786
- Sir William Jones Sanskrit, Greek and Latin have “sprung from some common source, which, perhaps, no longer exists” — the birth of Indo-European, and the proof that a lost tongue can be recovered from its children.
- 1818–1822
- Rasmus Rask, Jacob Grimm The sound shifts stated as rules: a k that becomes an h, in every word, is kinship.
- 1884
- Karl Abel, Über den Gegensinn der Urworte The oldest words carried opposite meanings; Freud took the idea up in 1910.
- 1903
- Holger Pedersen Coins Nostratic — our languages: Indo-European kin to Semitic, Uralic, Altaic and more.
- 1905
- Alfredo Trombetti, L’unità d’origine del linguaggio The unity of origin of language argued in full — and dismissed by the field for a century.
- 1960s–1984
- Vladislav Illich-Svitych, Aharon Dolgopolsky The Nostratic comparative dictionary. Illich-Svitych died at thirty-one with the first volume unfinished; his colleagues finished it.
- 1987–2002
- Joseph Greenberg Mass comparison. Language in the Americas; Eurasiatic. His classification of Africa’s languages was dismissed, then adopted.
- 1994
- Merritt Ruhlen; Bengtson & Ruhlen The Origin of Language; “Global Etymologies”: twenty-seven roots proposed for every language on earth.
- 1995
- Saul Levin Semitic and Indo-European: The Principal Etymologies — a professor of Hebrew and Greek argues that the two families share roots.
- 1997–2014
- Georges Bohas The theory of matrices and etymons: Arabic vocabulary built from two-consonant cores whose phonetic features carry meaning.
- 1998–2005
- Sergei Starostin The Tower of Babel database; Borean, the macro-family above Nostratic.
- 2008
- Allan Bomhard; Dolgopolsky Reconstructing Proto-Nostratic; the Nostratic Dictionary. The reconstruction in full.
- 2010
- Edward Vajda Dene–Yeniseian: Ket, in Siberia, shown to be kin to Navajo, across the Bering Strait and more than ten thousand years.
- 2013
- Pagel, Atkinson, Calude & Meade Ultraconserved words: some words persist fifteen thousand years and more across the Eurasiatic families.
- 2016
- Blasi and colleagues Sound–meaning associations found across two-thirds of the world’s languages: n and the nose, r and roundness, l and the tongue.