The word "un-alike" means not similar or dissimilar. The antonyms for "un-alike" are "alike" and "similar". "Alike" refers to two or more things that are very similar in appearance, nature, or characteristics. For instance, "The two sisters look alike." "Similar," on the other hand, denotes the features that match each other up to a certain degree. For instance, "The designer created two dresses that are similar in style, but differ in color." Hence, "alike" and "similar" have opposite meanings to "un-alike" and are often used to show how different or alike two things are from one another.