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Dictionary of Maya Hieroglyphs

Thompson’s catalogue of Maya signs
by Peter Mathews

The year 1962 saw the publication of a major new book in Maya studies: J. Eric S. Thompson’s A Catalog of Maya Hieroglyphs (1962). Actually, "Thompson’s Catalog", as the book is widely referred to, was one of the first books that I read in the field of Maya studies. I can still remember as a schoolboy visiting the Australian National Library and looking up books in their collection on the Classic Maya. There were only two: one was Alfred Maudslay’s (1889-1902) great study of Maya sites and monuments, and the other was Thompson’s Catalog. I remember opening Thompson’s book and wondering "What is this?" At first sight the Catalog seemed to be a meaningless jumble of numbers with a few drawings of hieroglyphs thrown in for good measure.

It was only after reviewing it more that I began to understand the book’s importance. Thompson’s Catalog represented just what it said: it was a catalogue of most of the glyphs known up to the time of its publication. Especially over the couple of decades after its publication it was a critical tool, for in that period few signs could be read with any certainty. With Thompson’s Catalog it was easier to refer to a sign as "T110" rather than to something like "that squished sign with the ends marked off and parallel lines along the middle". It was also easy to check all examples of a particular sign for comparison purposes, and the ability to do that easily (using Thompson’s Catalog) greatly aided the decipherment process.

I might add another personal anecdote here. When I started studying Maya glyphs under the expert guidance of David Kelley, he suggested that I take the Palenque inscriptions and make my own transcription of its hieroglyphs, and then compare my findings with the entries in Thompson’s Catalog. This I did, and then I checked my results with Dave, especially those in which my analysis differed from those of Thompson. And in our many late night discussions, Dave Kelley would patiently explain why, in the vast majority of cases, I was wrong and Thompson was right. (Every now and again he’d rub his hand over the top of his head and say "well, yes, I think you’re right on this one" and absolutely make my week!) Through those many sessions with Dave Kelley, which are still among my fondest memories, I learned a tremendous amount about Maya glyphs and the variability of signs, and in the process got to know Thompson’s Catalog inside out.

Thompson’s Catalog is considerably more useful than other Maya sign catalogues that have been produced (see Earlier Glyph Dictionaries). It is the most complete catalogue that has been compiled, and includes glyphs from both the codices and the monuments. It is reasonably good on the identification of individual, distinct signs. And finally, Thompson’s Catalog has a numbering system that allows for expansion as new signs are identified.

This does not mean that there are no problems with Thompson’s Catalog. In some cases more than one distinct sign is included under one number, and there is at least one case of a well-known sign not being included in the catalogue. Many numbers have turned out to be allographs, in other words variant forms of signs that have already been designated. The "portrait" signs, or head variants, in particular have many problems.

Thompson completed his Catalog by compiling what he called his "gray cards" or "gray sheets"; they have since become known as "Thompson’s gray cards". These represent the basic data sheets that form the basis of the catalogue. Thompson gathered together virtually every glyph known at that time, and "sorted" them by their "main sign". He describes the process in detail in the Catalog (Thompson 1962:5-9).

How to use Thompson’s catalogue

Essentially, each one of Thompson’s entries represents a glyph block. Glyph blocks are the individual lozenge-shaped squares that together make up hieroglyphic texts. "Glyph block" is the term for the physical form, when talking about them as units of writing, they are called glyphs. The individual elements that combine to make up a glyph (within the glyph block) are called signs: these are the smallest meaningful units of the writing system. 1 

The individual glyphs that Thompson transcribes in his Catalog entries are made up of from one to about seven of eight signs. Long ago it was established that the reading order within the glyph is the same as that in hieroglyphic texts: left to right and top to bottom. In other words, the sign which occupies the top left corner of the glyph block should be read first, and that which occupies the lower right corner should be read last. Of course there are sometimes exceptions to this rule, but they are usually clear from context–by comparing them with other examples of the same glyph.

Thompson emulated Zimmermann in using a punctuation system to separate the individual signs. A period (or what I and Simon Martin and other Aussies and Pommies call a "full stop") separates signs that are arranged left to right, and colons separate signs arranged one above the other. In othe words, a glyph that is transcribed Tl.602:25:178 means that sign Tl is arranged to the left of three signs stacked vertically–T602 on top, T25 in the middle, and T178 below. The sign under which the entry lies (in the above example it would be the largest of the signs, T602 [Thompson called these large signs "Main Signs", and the smaller, thinner ones "Affixes"]). A couple of other conventions are used. Square brackets around a sign indicates that that sign (or its diagnostic features) is infixed inside the sign that is listed before it. In other words T644[528] means that the critical features of T528 are infixed inside T644. Finally, a dash indicates that two signs are fused together in what is called a conflation.

Before recording the transcription of each entry, Thompson lists the example number, as he inventoried the glyphs in his gray cards. After listing each entry, Thompson records the provenance of the example, listing the site, monument, and position in the hieroglyphic text. Thompson’s site and inscription designations are recorded in a rather ad hoc fashion. More recently a three letter site designation has been developed by Ian Graham of the Corpus of Maya Hieroglyphic Inscriptions project (CMHI 1:23-24; 3:185-187; 6:187-189). This code is now universally used by Mayanists.

Additions to the Thompson’s catalogue

As was said above, Thompson’s Catalog is not perfect. For example, now that we have more understanding of Maya hieroglyphs, it is clear that the distinction between Thompson’s "Affixes" and "Main Signs" is purely arbitrary, and has no implications for meaning or relative importance. In addition, there are many signs that he has listed as distinct but which are now considered to be stylistic variations of one another. Conversely, in some cases, there are signs listed by Thompson that in fact contain two or more distinct signs. And finally, over the years new signs–ones that Thompson has not included in his catalogue–have been discovered. All this means that a re-evaluation of Thompson’s catalogue signs is called for.


  1. I use here the terms that are almost universally used at the present time. It should be noted that David Kelley (for example in his great book Deciphering the Maya Script [1976]) used different terms. What I am calling here a glyph, David Kelley calls a glyph group, or "glyger"; what I call a sign he calls a glyph.

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