What does dissimilation mean?
Dissimilation is the process by which two similar or identical sounds in a word become less alike, typically because repeating them is difficult to pronounce. A well-known example is English 'marble', which developed an 'l' where older forms had a second 'r' (from French marbre); similarly, Latin peregrinus yielded English pilgrim through successive sound changes. The term belongs chiefly to linguistics and phonetics, though it also has a biological sense describing the breakdown of complex substances into simpler ones within an organism — roughly the opposite of assimilation in both fields. In linguistics, dissimilation is treated as a natural, often regular historical change rather than an error, and it helps explain why many common words have unexpected letters. Because it operates silently across generations of speakers, dissimilation offers a vivid reminder that pronunciation is shaped as much by the limits of the human mouth as by any formal rule.
In linguistics, the process by which one of two similar or identical sounds in a word changes so as to become less like the other.
"The shift from marbre to marble involved dissimilation of the second r."
Most commonly encountered in historical linguistics and phonetics discussions of sound change.
In biology, the metabolic process of breaking down complex substances into simpler ones within an organism; catabolism.
"Respiration is a form of dissimilation in which glucose is broken down to release energy."
Rarely pluralized except in technical discussions referring to multiple instances of the process.
"Several distinct dissimilations can be traced through the history of Romance languages."
Say 'marble' out loud: that second consonant isn't an accident — dissimilation quietly swapped a French 'r' for an 'l' so your tongue wouldn't have to say 'r' twice.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dissimilation
Dissimilation derives from Latin dissimilis, meaning 'unlike', formed from dis- ('apart') plus similis ('like'). It entered English in the early 17th century, first in general use meaning differentiation, before being adopted as a technical term in 19th-century comparative philology to describe sound change. It shares its root with similar, simulate, simile, and its linguistic opposite, assimilation.
Related word forms
How dissimilation is actually used
Dissimilation is a technical term used chiefly in linguistics, phonetics, and biochemistry; it is rare in everyday conversation. In linguistics it is largely descriptive rather than evaluative. The biological sense overlaps with 'catabolism' but is somewhat older and less frequent in modern scientific writing.
Easily confused with dissimilation
Assimilation makes sounds more alike (as in 'input' from 'in-put'), while dissimilation makes them less alike.