Kangaroo Words

Written by on March 11, 2018 in LISP, Natural Language Processing, Programming with 0 Comments

According to Wikipedia, “A kangaroo word is a word that contains letters of another word, in order, with the same meaning. For example: the word ‘masculine’ contains the word ‘male’, which is a synonym of the first word; similarly, the word ‘observe’ contains its synonym ‘see’.”

Interesting idea. The key point to note is that the contained word must have similar meaning; it cannot be any arbitrary word. iLexicon has special annotations for such kangaroo words, and that is the focus of today’s post.

Let us first check if iLexicon knows that masculine is a kangaroo word.

cg-user(10): (kangaroo-get-contained-words “masculine”)


The function kangaroo-get-contained-words takes a word and returns one or more words with similar meaning, if the given word is a kangaroo word. If the given word is not a kangaroo word, the function returns nil.

What about the other example mentioned in Wikipedia: observe?

cg-user(11): (kangaroo-get-contained-words “observe”)


Let us try to give a word that is not a kangaroo word and check:

cg-user(12): (kangaroo-get-contained-words “zone”)


If you notice, the word zone contains another word within it: one, but that is not a synonym for zone. Hence it is not a kangaroo word.

As you have seen in earlier posts,  iLexicon contains several interesting filters. Let us combine a couple of them with kangaroo word identification.

The following retrieves 8-letter kangaroo words that are also onomatopoeic:

cg-user(13): (get-matching-words :kangaroo t :num-letters 8 :onomatopoeia 1)

(“splatter” “splutter”)

That is interesting! But how do we check if these words are kangaroo words?

cg-user(14): (kangaroo-get-contained-words “splatter”)


cg-user(15): (kangaroo-get-contained-words “splutter”)

(“utter” “sputter”)

We can confirm that splatter and spatter are synonyms, and so are splutter and sputter. iLexicon includes utter as a sub-word of splutter because of close similarity, even though they are not exact synonyms.

Here are a few more kangaroo words:

cg-user(16): (loop for word in ‘(“diskette” “distressed” “dosage” “drugget” “fatigue”)

      do (print (kangaroo-get-contained-words word)))






These (and many more) kangaroo words are marked as such in iLexicon because they appear to be an interesting category of words. As of now, I cannot think of any special context or application where they can be directly used. I am sure something interesting will come up in future, and iLexicon will be great value addition at that point!

Have a great weekend!

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