The Secret Life of Words

The hidden machinery behind the humble word.

Posted August 22, 2025 | Reviewed by Monica Vilhauer Ph.D.

In the beginning was the Word.

-John 1:1, King James Bible

I know nothing in the world that has as much power as a word.

-Emily Dickinson, Letters

Words are, in my not-so-humble opinion, our most inexhaustible source of magic.

-J.K. Rowling, Harry Potter and the Deathly Hallows

It’s not hard to find sage quotes about words. It’s much harder to define them.

The American Heritage Dictionary tried: “A sound or a combination of sounds... that symbolizes and communicates a meaning....” Yet, we frequently utter communicative sounds like the indignant “psh,” the contemplative “hmm,” the pejorative “shh,” or the befuddled “mmm?” Are they words? Most would say no, yet they seem to satisfy the dictionary definition.

The Stanford Encyclopedia of Philosophy tried harder. They devoted over 17,000 words—whatever they are—to the topic of words. Foreshadowing the complexity of the matter, the entry starts with an understated heads-up to the reader, "The notions of word and word meaning are hard to pin down”, and then proceeds to review dozens of ideas, problems, and controversies, citing over 200 references. 1

The Oxford Handbook of the Word also gave it a go, dedicating 42 chapters and over 800 pages to the understanding of the word . The volume starts with an introductory sentence by the editor, “Words are the most basic of linguistic units,” and ends with a chapter by Alison Wray titled, “Why are we so sure we know what a word is”. 2 Linguist Martin Haspelmath agreed with Wray, noting that there is “no clear definition of word. ” He took a stab himself: “A word is (i) a free morph, or (ii) a clitic, or (iii) a root or a compound possibly augmented by nonrequired affixes and augmented by required affixes if there are any”. 3

In the beginning was the... free morph, or a clitic, or a root or a compound possibly augmented by nonrequired affixes and augmented by required affixes if there are any? Psh!

How is it that words can be so common, so fundamental, yet so elusive? A key discovery is that words are not just a sound pattern ( cat , gato , neko ) and a meaning (furry-domesticated-meows), but also contain something in between, a kind of “middle word,” which psycholinguists refer to as a lemma . The name comes from mathematics, where it refers to an intermediate step in a theorem. You can think of word lemmas as the hidden network that computes the translation between word sound and word meaning. How do we know lemmas exist? There are several bits of evidence, including computational arguments, neural network simulations, and behavioral studies showing that when people get themselves into tip-of-the-tongue states—a failure to access the sound pattern of a word—they know more about the word than just its meaning, such as fragments of its syntactic properties. 4 There’s another fascinating source of evidence, though: neurological cases in which people appear to have lost their middle-word realm altogether.

The classic case of Mr. Schwarz is a good example. On the night of 16 May 1884, Mr. Schwarz became restless, talked in his sleep, and wandered about. At 4:00 AM, his wife knew there was something seriously wrong. His speech was “mutilated”, and he didn’t answer questions. Despite efforts to communicate, he just kept repeating the same nonsense expressions. He was taken to the hospital where he was evaluated by Dr. Ludwig Lichtheim, who jotted the following report. 5

“Patient is a rather fat, pale, man. Features flabby; expression dull. On admission, he gave the impression of a subject with psychical deficiencies. He talked a good deal, but repeated the same phrases. He points to his head and says, ‘Oh how stupid I am, I cannot,’ &c. It is difficult to make anything out of him, for he understands little that is said to him; but it is easy to ascertain that he is in possession of his intelligence , and that the apparent psychical deficiency consists only in his difficulty in understanding others, and in making himself understood. His actions leave no doubt on this point.”

More comprehensive evaluation confirmed significantly impaired comprehension. “If one stands behind him and talks to him, he turns round and asks: ‘Do you speak to me?’ The simplest requests … are answered by: ‘I don’t know what one wants.’” Speech production was fluent but error-prone: “He talks a good deal in a flowing manner: he is seldom short for a word; occasionally uses a wrong or a mutilated one.” Lichtheim further reported that “He is in great difficulty when he has to name objects shown to him; he finds the names with the greatest difficulty, and assists himself with descriptions. Instead of ‘wine,’ he says ‘that is strong;’ for ‘water,’ ‘that is weak,’ &c.” He clearly had the meaning of the word he was looking for but couldn’t get to the word itself.

So far, these symptoms are consistent with a severe form of fluent aphasia, so-called Wernicke’s aphasia , in which comprehension is impaired alongside fluent but paraphasic (error-prone) speech production. A decade earlier, Carl Wernicke explained his namesake syndrome as damage to the memory of the sound pattern of words. Comprehension is impaired on this account because the sounds simply don’t register as recognizable words, and speaking is “mutilated” because the patient can’t call up how the words are supposed to sound in the first place. But Lichtheim tested another ability that indicated something different for his patient. Mr. Schwartz could “repeat correctly all that was spoken before him” even while he couldn’t understand what he was parroting. Mr. Schwartz, then, had no trouble deciphering the sound of words, nor translating those sounds, once aroused, into intelligible speech; and he had no trouble with the meaning of things themselves. His trouble was in the linking of sounds with meanings and meanings with sounds.

Mr. Schwarz was the first reported case of transcortical sensory aphasia , interpreted by Lichtheim as a severing of the connection between intact word sounds and intact word meanings, a disruption of the elusive lemma system in modern terms. Recent efforts to map the location of this system supports Lichtheim’s conclusion. The brain’s realm of the middle word can be found in a zone of the temporal lobe that lies between areas that code the sound patterns of language and semantics, as shown in the figure here.

In recent years, this middle-word realm has grown richer in composition, and intrigue. Rather than just connecting sounds and meanings of words , research in language science has pointed to a broader role for this system in the mapping between sentences and meanings, which implicates an even more vexing linguistic domain: syntax, the grammar of language. 6 Words, then, appear to be the surface forms an entire underworld of linguistic complexity.

Perhaps that’s why words are simultaneously so basic, yet so elusive. They are our linguistic user interface, like a computer GUI, that harbors and hides much of the behind-the-scenes intricacy of human language.

Excerpted and adapted from “Wired from Words: The Neural Architecture of Language” by Gregory Hickok, a forthcoming book published by MIT Press, available for pre-order prior to November 2025 publication.

Word meaning. Stanford Encyclopedia of Philosophy . < https://plato.stanford.edu/entries/word-meaning/ >.
Taylor, J. R. E. The Oxford handbook of the word . (Oxford University Press, 2015).
Haspelmath, M. Defining the word. Word 69, 283-297 (2023).
Vigliocco, G., Antonini, T. & Garrett, M. F. Grammatical gender is on the tip of Italian tongues. Psychological science 8, 314-317 (1998).
Lichtheim, L. On aphasia. Brain 7, 433-484 (1885).
Krauska, A. & Lau, E. Moving away from lexicalism in psycho- and neuro-linguistics. Frontiers in Language Science 2 (2023). https://www.frontiersin.org/journals/language-sciences/articles/10.3389/flang.2023.1125127/full

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Greg Hickok, Ph.D., is Distinguished Professor at the University of California, Irvine, and the author of the forthcoming book Wired for Words.

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