1. 1. Belonging equally to or shared equally by two or more; joint: common interests.
   2. Of or relating to the community as a whole; public: for the common good. See Usage Note at mutual.
   3. Occurring frequently or habitually; usual.
   4. Most widely known; ordinary: the common housefly.
   5. Not distinguished by superior or noteworthy characteristics; average: the common spectator.
   6. Of no special quality; standard: common procedure.
   7. Of mediocre or inferior quality; second-rate: common cloth.
   8. Either masculine or feminine in gender.
   9. Representing one or all of the members of a class; not designating a unique entity.
2. Widespread; prevalent.
3. 1. Occurring frequently or habitually; usual.
   2. Most widely known; ordinary: the common housefly.
   3. Not distinguished by superior or noteworthy characteristics; average: the common spectator.
   4. Of no special quality; standard: common procedure.
   5. Of mediocre or inferior quality; second-rate: common cloth.
   6. Either masculine or feminine in gender.
   7. Representing one or all of the members of a class; not designating a unique entity.
4. Having no special designation, status, or rank: a common sailor.
5. 1. Not distinguished by superior or noteworthy characteristics; average: the common spectator.
   2. Of no special quality; standard: common procedure.
   3. Of mediocre or inferior quality; second-rate: common cloth.
   4. Either masculine or feminine in gender.
   5. Representing one or all of the members of a class; not designating a unique entity.
6. Unrefined or coarse in manner; vulgar: behavior that branded him as common.
7. Grammar
   1. Either masculine or feminine in gender.
   2. Representing one or all of the members of a class; not designating a unique entity.

1. commons The common people; commonalty.
2. commons (used with a sing. or pl. verb)
   1. The social class composed of commoners.
   2. The parliamentary representatives of this class.
3. The House of Commons. Often used in the plural.
4. A tract of land, usually in a centrally located spot, belonging to or used by a community as a whole: a band concert on the village common.
5. The legal right of a person to use the lands or waters of another, as for fishing.
6. commons (used with a sing. verb) A building or hall for dining, typically at a university or college.
7. Common stock.
8. Ecclesiastical A service used for a particular class of festivals.

Synonyms: These adjectives describe what is generally known or frequently encountered. Common applies to what takes place often, is widely used, or is well known: The botanist studied the common dandelion.
The term also implies coarseness or a lack of distinction: My wallet was stolen by a common thief.
Ordinary describes something usual that is indistinguishable from others, sometimes derogatorily: A ballpoint pen is adequate for ordinary purposes. The critic gave the ordinary performance a mediocre review.
Familiar applies to what is well known or quickly recognized: Most children can recite familiar nursery rhymes.
Vulgar describes association with the great mass of people and often connotes lack of refinement: "He [Shakespeare] was not something sacred and aloof from the vulgar herd of men" (William Hazlitt). See Also Synonyms at general.