Dissimilar and similar are exact opposites built on one root. Similar means alike in nature or appearance without being identical — two things that resemble each other. Dissimilar is its formal negation: unlike in nature or kind, not alike. The dis- simply reverses similar, so where similar claims resemblance, dissimilar denies it. Both take 'to' — similar to, dissimilar to — and dissimilar is the more formal way to say 'unlike'.
This pair is the clean case of a word and its own negation. Similar comes from Latin similis, 'like', and means resembling without being the same. Dissimilar is that word with dis- bolted on to reverse it — unlike in kind, differing in nature. Unlike 'different', which comes from a separate root and simply says 'not the same', dissimilar carries the exact stamp of similar denied, which makes it the more formal, more precise negative: two dissimilar approaches are unlike in their very nature, not merely non-identical. The symmetry runs down to the grammar, since both keep the preposition 'to'.
dissimilar
Dissimilar means unlike in nature or kind — different not by a shade but at the root. It is built from dis-, 'not', and the Latin similis, 'like', the same root as 'similar' and 'resemble'. The word leans formal and is often technical: engineers warn that dissimilar metals in contact will corrode, because the gap between them is real enough to drive a current. To call two things dissimilar is to say they are other in kind, and usually that the contrast is plain enough to distinguish at a glance.
similar
Similar means alike — sharing qualities or appearance without being the same. It comes from the Latin similis, 'like', the root behind 'resemble', 'assimilate', and 'simile'. Two things are similar when they correspond closely enough to invite comparison, yet stay distinct, so that you might draw an analogy between them. The standard preposition is 'similar to'. It is gentler than 'identical', which claims full sameness, and it is the natural opposite of different.
| dissimilar | similar | |
|---|---|---|
| Meaning | unlike in nature or kind; not alike | alike without being identical |
| Relationship | the exact negation of similar | the base word (Latin similis, 'like') |
| Register | formal — stronger than 'not similar' | everyday, common |
| Preposition | dissimilar to | similar to |
| Versus 'different' | same idea, but marked as similar-denied | 'different' is a separate root |
| The picture | unlike metals driving a current | matched pendulums swinging as one |
The unlike metals and the matched pendulums. Similar is the two pendulums of equal length keeping perfect time — alike enough to move as one. Dissimilar is the copper and zinc, unlike enough that the gap between them lights a circuit. The dis- just flips similar over: resemblance becomes its denial. Ask whether things are alike or unlike in kind. Alike, resembling: similar. Unlike, differing in nature — and said formally: dissimilar. Both take 'to'.
dissimilar
- iThe two dialects are so dissimilar that speakers struggle to follow one another.
- iiTheir methods were wholly dissimilar, though the goal was the same.
- iiiNot dissimilar to last year's design, the new model refines rather than reinvents.
similar
- iThe two cases are broadly similar.
- iiHer handwriting is similar to her mother's.
- iiiWe reached similar conclusions by different routes.
Keep one technical sense out of the vocabulary contrast: in arithmetic, similar and dissimilar fractions simply mean fractions with the same or different denominators — a fixed mathematical label with nothing to do with resemblance in the ordinary sense. A learner who meets 'dissimilar fractions' in a maths lesson and 'dissimilar approaches' in an essay is meeting two unrelated uses of the word. How similar differs from plain different — resemblance against mere non-sameness — is drawn on its own page in the 'Related' list below.