Kangaroo word is a playful term for a word that carries within it a synonym of itself. Examples include regulate (rule), indolent (idle), and encourage (urge).
Generally, the synonym (called a joey) within a kangaroo word should be the same part of speech as the kangaroo word and its letters should appear in order (though usually spaced out). The term kangaroo word was popularized by author Ben O’Dell in a short article in The American Magazine, published in 1956.
Origin of the Word
Kangaroo words are so named because they carry their synonyms with them as a kangaroo would its joey. Anu Garg, author of Another Word a Day: An All-New Romp Through Some of the Most Unusual and Intriguing Words in English, explains what qualifies a kangaroo word.
Why do we call them kangaroo words? Not because they originated in Australia. Rather, these are marsupial words that carry smaller versions of themselves within their spellings.
How do they qualify?
How do they look like?
‘respite’ has ‘rest,’ ‘splotch’ has ‘spot,’ ‘instructor’ has ‘tutor,’ and ‘curtail’ has ‘cut.’
Sometimes a kangaroo word has more than one joey. The word ‘feasted’ has a triplet, ‘fed,’ ‘eat,’ and ‘ate.’
Finally, two qualifications: the joey word has to have its letters in order within the parent kangaroo word, but if all the letters are adjacent, for example, enjoy/joy, it doesn’t qualify,” (Garg 2005).