similar

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Related in appearance or nature; alike though not identical.
2. adj. Mathematics Having corresponding angles equal and corresponding line segments proportional. Used of geometric figures: similar triangles.

Century Dictionary and Cyclopedia

1. Having characteristics in common; like in form, appearance, size, qualities, relations, etc.; having a more or less marked resemblance to each other or one another; in some respects identical; bearing a resemblance, as to something implied or specified: as, the general features of the two landscapes are similar; the plans are similar.
2. Homogeneous; of like structure or character throughout.
3. In geometry, of the same shape: said of two figures which have all their corresponding angles equal, whence it will follow, for ordinary Euclidean space, that all their corresponding lengths will be proportional, that their corresponding areas will be in the duplicate ratio of their lengths, and that their corresponding volumes will be in the triplicate ratio of their lengths. In the non-Euclidean systems of geometry these consequences are falsified, so that there are no similar figures.
4. In biology, alike in some respects; identical to some extent. Specifically— Having the like structure; of common origin; homologous (which see)
5. In music, in the same direction: said of the rising and falling of two voice-parts.
6. n. That which is similar; that which resembles something else in form, appearance, quality, etc.; in the plural, things resembling one another.
7. n. The homeopathic principle of administering drugs. See similia.
8. In the theory of aggregates, similarly arranged; coupled by a one-one relation.

Wiktionary

1. adj. Having traits or characteristics in common; alike, comparable.
2. adj. mathematics Of geometrical figures including triangles, squares, ellipses, arcs and more complex figures, having the same shape but possibly different size, rotational orientation, and position; in particular, having corresponding angles equal and corresponding line segments proportional; such that one can be had from the other using a sequence of operations of rotation, translation and scaling.
3. n. That which is similar to, or resembles, something else, as in quality, form, etc.
4. n. homeopathy A material that produces an effect that resembles the symptoms of a particular disease

GNU Webster's 1913

1. adj. Exactly corresponding; resembling in all respects; precisely like.
2. adj. Nearly corresponding; resembling in many respects; somewhat like; having a general likeness.
3. adj. rare Homogenous; uniform.
4. n. That which is similar to, or resembles, something else, as in quality, form, etc.

WordNet 3.0

1. adj. (of words) expressing closely related meanings
2. adj. resembling or similar; having the same or some of the same characteristics; often used in combination
3. adj. marked by correspondence or resemblance
4. adj. capable of replacing or changing places with something else; permitting mutual substitution without loss of function or suitability
5. adj. having the same or similar characteristics