The Cognātarium


The Cognātarium is a lexicon of English-language cognates; that is, words related by common origin. In English many words are formed from compounds of two or more word stems from the original language. In the great majority of words listed here in this lexicon, those original words stem from ancient Latin and Greek. For example, helicopter and pterodactyl both contain the root stem pter–, which means wing in the original Greek.

The Cognātarium divides all of the listed English words into their constituent parts, or morphemes. As of the date of this writing, The Cognātarium contains over 2,600 morphemes for your perusal. Morphemes are listed alphabetically.

It is not the intention of The Cognātarium to list all of the possible words related to any particular morpheme. In many cases the listings provide only a sampling of the related cognates so that you can have a good idea of how a particular morpheme is used in English.

Using The Cognātarium

The Cognātarium allows you to search for a particular morpheme, list the morphemes alphabetically, or search for a particular English word within the lexicon and find the morphemes that make up the subject word.

List Morphemes alphabetically

To see an alphabetically sorted list of morphemes, simply press one of the letter buttons at the top of this page. If you press F you will get a list of all morphemes that begin with the letter F.

Search for a Morpheme

To search for a particular morpheme, enter the morpheme (e.g., pter) into the search box at the top of this page and click Search Morphemes. The listing of words using the morpheme pter– will be displayed. You can enter a partial morpheme (e.g., pt and you will get a list of all morphemes beginning with pt–.

Search for a Word

To find an English word and see what morphemes the word comprises, enter the word in the search box at the top of this page and click Search Word List. All of those morphemes applying to the selected word will be listed. For example, enter pterodactyl in the search box and click Search Word List. You will find that pterodactyl comprises two morphemes: pter–, which means wing and dactyl–, which means finger. Thus a pterodactyl is a wing-finger—which makes sense, as a pterodactyl has wings on its fingers.

You can enter only partial words also: for example, entering plan will bring up all words containing that group of letters; so you will find implant, plan, plane, planet, plangent, plant, supplant, et al., which is probably more words than you want. There is a limit of 500 hits on the search, which should be more than enough for you.


For each morpheme there are several elements:

  1. The morpheme itself, at the beginning of the paragraph.
  2. The meaning of the morpheme, enlosed in curly braces.
  3. The list of English words containing and derived from the morpheme, using the exact spelling of the subject morpheme.
  4. Words also derived from the same morpheme, but with variant spelling.
  5. In some cases, foreign words derived from the same Latin, Greek, or other root.
  6. Same As morphemes, with a link to the morpheme. “Same as” means that the morpheme derives from the same root. For example plain– and plan– both are derived from the Latin word planus, which means level or flat.
  7. See also morphemes, with a link to the morpheme. “See also” means the named morpheme is related more distantly—in most cases by the same Indo-European root stem. For example, ped–¹ is Latin root that means foot. It is related to the Greek morpheme pod–, which also means foot. Both are derived ultimately from the Indo-European stem ped–, of the same meaning.
  8. In some cases, words that are not related to the subject morpheme, where one might logically think a word should be listed in the same group. For example, one might reasonably think that apoplexy derives from the morpheme plex– but in fact it does not.
  9. Other commentary on the subject morpheme and references to the appendices where applicable.
  10. The etymology of the morpheme, back to the original Indo-European root where possible. Most of the morphemes here are derived from Latin and Greek, but other languages have contributed to the development of English. (Author’s note: The listing of Indo-European roots for the morphemes is ongoing and not yet complete.)

Guide to the Symbols

Symbol Meaning
The green bullet lists words that are derived from the same morpheme, but have variant spelling.
The red bullet lists words that are not in fact related to the subject morpheme, although the reader might assume that they are related.
The blue bullet lists “Same as” stems, “See also” stems, and other commentary on the subject morpheme.
The aqua (cyan) bullet lists foreign words that are derived from the same morpheme.
||  This symbol marks the start of the etymology of the morpheme.
From This symbol in the etymology means “from” and indicates the source of the morpheme. For example “From Gr” means from Greek.
To This symbol in the etymology means “to” and indicates words that arise from the term to the left. For example “L pati To patiens” means that Latin patiens is derived from pati.
This asterisk symbol in the etymology means hypothetical, or not attested. It means that the root is hypothesized based on linguistic evidence, but that no written record of the stem has been found. All Indo-European roots are so marked, as we have no written evidence of the Proto-Indo-European language.
†  This dagger symbol means the origin is unknown.


In addition to the main morpheme listings, there some appendices that provide additional interesting information about the origins of English words. You can find a list of words derived from the names of gods and mythical beings, a list of words derived from American Indian languages, and other information. Select the Appendices link at the top of this page for a complete list of appendices.

Under Construction

This lexicon is perpetually under construction and will never be complete. The English language has hundreds of thousands of words and it is not feasible to list every word and every morpheme.

User Feedback

If you have comments, suggestions, or questions, I would be glad to hear from you. If you find an error in this lexicon or would like to suggest additions, please e-mail me. If you would like to praise or damn me, please send me a message. I will respond to all sincere messages. Please put “Cognatarium” or something similar in the subject line. Messages lacking a subject line are immediately deleted without opening, as they are most often spam, of which I receive more than my share.

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