asterism

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Printing Three asterisks in a triangular formation used to call attention to a following passage.
2. n. Astronomy A cluster of stars smaller than a constellation.
3. n. Mineralogy A six-rayed starlike figure optically produced in some crystal structures by reflected or transmitted light.

Century Dictionary and Cyclopedia

1. n. A group of stars: formerly equivalent to constellation, but now appropriated to any small cluster of stars, whether a part of a constellation or not.
2. n. An asterisk, or mark of reference.
3. n. Three asterisks placed thus, , or thus, , before a passage, to direct attention to it.
4. n. An optical property exhibited by some crystallized minerals which show a star-shaped luminous figure when viewed by reflected light, as the asteriated sapphire, or by transmitted light, as some kinds of phlogopite. In the former case it is due to certain peculiarities of internal structure, in the latter to the inclusion of symmetrically arranged acicular crystals.

Wiktionary

1. n. A small group of stars that forms a visible pattern but is not an official constellation.
2. n. A rarely used typographical symbol (⁂, three asterisks arranged in a triangle), used to call attention to a passage or to separate sub-chapters in a book.
3. n. A star-shaped figure exhibited by some crystals by reflected light (as in a star sapphire) or by transmitted light (as in some mica).

GNU Webster's 1913

1. n. A constellation.
2. n. A small cluster of stars.
3. n. An asterisk, or mark of reference.
4. n. Three asterisks placed in this manner, ⁂, to direct attention to a particular passage.
5. n. An optical property of some crystals which exhibit a star-shaped by reflected light, as star sapphire, or by transmitted light, as some mica.

WordNet 3.0

1. n. (astronomy) a cluster of stars (or a small constellation)
2. n. (mineralogy) a star-shaped figure with six rays that is seen in some crystal structures under reflected or transmitted light