Dissimilar and unalike both mean 'not alike', and they are very close — but each leans a shade differently. Dissimilar means different in nature or kind: other at the root, the formal and often technical word (think 'dissimilar metals'). Unalike means sharing no resemblance, failing to correspond: the plainer word, stressing that nothing in the one matches the other. Same idea — not the same — but dissimilar points at a difference of kind, unalike at a simple lack of likeness.
These are unusually close synonyms, so the axis is fine but real, and the physics behind each word marks it. Dissimilar is dis- ('not') plus the Latin similis ('like'): a difference in composition or kind, real enough that two dissimilar metals in an electrolyte will set up a current and corrode. Unalike is the plain un- ('not') plus 'alike': a lack of correspondence, like tuning forks of different lengths — strike one and the unalike ones never answer. So dissimilar leans on being other in kind; unalike on sharing no matching likeness.
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.
unalike
Unalike means not alike — sharing no resemblance, failing to correspond. It is built plainly from un-, 'not', and 'alike', and it usually describes two things set side by side that simply do not match: two unalike siblings, two unalike halves. Where dissimilar leans formal and technical, unalike is the plainer word, and it stresses the absence of any answering likeness — nothing in the one echoes the other. It almost always follows what it describes ('the two are unalike') rather than standing before a noun.
| dissimilar | unalike | |
|---|---|---|
| Meaning | different in nature or kind | sharing no resemblance |
| Emphasis | other at the root; a real difference of kind | no matching likeness; failure to correspond |
| Register | formal, often technical | plainer, more everyday |
| Often with | dissimilar to / dissimilar metals | utterly / completely unalike |
| Root | Latin similis, 'like' (dis- + similar) | plain English: un- + alike |
| Example | two chemically dissimilar minerals | two siblings, utterly unalike |
Picture two benches. Two metals — copper and zinc — in one beaker, so different in kind that wiring them together makes a current and eats one away: that difference at the root is dissimilar. A struck tuning fork whose only answer comes from the one fork of the same length, while the rest stand silent: that lack of any matching likeness is unalike. Both mean 'not the same'; dissimilar stresses a difference of kind, unalike a simple absence of resemblance. For composition or category, reach for dissimilar; for 'they just don't match', reach for unalike.
dissimilar
- iThe two minerals are chemically dissimilar, however alike they look.
- iiHer method is wholly dissimilar to her mentor's.
- iiiDissimilar metals in contact will corrode over time.
unalike
- iThe twins are physically alike but temperamentally unalike.
- iiHowever you compare them, the two accounts are utterly unalike.
- iiiTheir tastes are so unalike that they never agree on a film.
They are nearly interchangeable, and in everyday use you can swap them. The fine tell: dissimilar leans on a difference of nature or kind (and carries the technical 'dissimilar metals'), while unalike leans on a plain lack of resemblance or correspondence. Dissimilar is the more formal choice; unalike is plainer and almost always comes after the noun ('the two are unalike').