What does dissimilar mean?
Dissimilar is an adjective meaning not alike: it describes two or more things that differ in nature, character, appearance, or some other respect. Formed by adding the negative prefix dis- to similar, it carries an air of precision and formality, which makes it a staple of scientific papers, legal documents, and analytical prose — a study might compare dissimilar populations, or a contract might govern parties with dissimilar interests. In everyday conversation, simpler words like different or unlike usually take its place. Grammatically, dissimilar behaves like other comparative adjectives: things can be dissimilar to something (the pattern favoured in British English) or dissimilar from something (more common in American English), and writers often specify the dimension of difference with dissimilar in — as in dissimilar in size or outlook. Its noun form, dissimilarity, names the state or degree of being unlike. For anyone writing with clarity and authority, dissimilar offers a concise way to signal genuine, meaningful difference rather than mere variation.
adjectiveNot alike; different in nature, quality, form, or character.
- Not alike; different in character, quality, or appearance.
"Though the twins were dissimilar in temperament, they shared a dry sense of humour."
"The two proposals were dissimilar in almost every respect except their cost."
"Researchers compared cells that were morphologically dissimilar but functionally equivalent."
Add three letters to "similar" and you get its exact opposite — the prefix dis- has been flipping meanings since Latin.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dissimilar
Dissimilar derives from Latin dissimilis, meaning "unlike", formed from dis- (expressing separation or negation) plus similis ("like" or "similar"). The word entered English via French in the late Middle English period, with written evidence dating to around the fifteenth century. It belongs to a broad family of words built on the Latin root similis, including similar, simulate, assimilate, and resemblance (through French), all of which preserve the underlying idea of likeness or comparison.
Related word forms
How dissimilar is actually used
Dissimilar is somewhat formal and appears most often in academic, scientific, and legal writing rather than everyday speech, where "different" or "unlike" are preferred. It typically takes the prepositions "to" (especially in British English), "from" (common in American English), or occasionally "in" when specifying the respect in which things differ.
Easily confused with dissimilar
"Similar" means having qualities in common, while "dissimilar", formed with the negative prefix dis-, means the opposite — not alike.
"Dissemble" is a verb meaning to hide one's true feelings or intentions, whereas "dissimilar" is an adjective simply describing things that are unlike each other; the two share only a superficial resemblance in spelling.