com·mon 
(kŏmən)
(kŏmən)adj. com·mon·er, com·mon·est
1.
a. Belonging equally to or shared equally by two or more; joint: common interests.
b. Of or relating to the community as a whole; public: for the common good.
2. Widespread; prevalent: Gas stations became common as the use of cars grew.
3.
a. Occurring frequently or habitually; usual: It is common for movies to last 90 minutes or more.
b. Most widely known; ordinary: the common housefly.
4. Having no special designation, status, or rank: a common sailor.
5.
a. Not distinguished by superior or noteworthy characteristics; average: the common spectator.
b. Of no special quality; standard: common procedure.
c. Of mediocre or inferior quality; second-rate: common cloth.
6. Unrefined or coarse in manner; vulgar: behavior that branded him as common.
7. Grammar
a. Either masculine or feminine in gender.
b. Representing one or all of the members of a class; not designating a unique entity.
n.
Idiom: 1. commons The common people; commonalty.
2. commons(used with a sing. or pl. verb)
a. The social class composed of commoners.
b. The parliamentary representatives of this class.
3. Commons The House of Commons.
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.
in common
Equally with or by all.
[Middle English commune, from Old French commun, from Latin commūnis; see mei-1 in the Appendix of Indo-European roots.]
common·ly adv.
common·ness n.
Synonyms: common, ordinary, familiar
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: "His neighbors were all climbing into their cars and trucks and heading off to work as if nothing miraculous had happened and this were just another ordinary day" (Steve Yarbrough).
Familiar applies to what is well known or quickly recognized: Most children can recite familiar nursery rhymes. See Also Synonyms at general.
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: "His neighbors were all climbing into their cars and trucks and heading off to work as if nothing miraculous had happened and this were just another ordinary day" (Steve Yarbrough).
Familiar applies to what is well known or quickly recognized: Most children can recite familiar nursery rhymes. See Also Synonyms at general.