A collection of all the objects isomorphic to a given object. Talking about the isomorphism class (of a poset, say) ensures that we will only consider its properties as a poset, and will not consider other incidental properties it happens to have.
[ahy-suh-mawr-fuh s] /ˌaɪ səˈmɔr fəs/ adjective, Chemistry, Crystallography. 1. (of a compound or mineral) capable of crystallizing in a form similar to that of another compound or mineral, used especially of substances so closely related that they form end members of a series of solid solutions.
[ahy-suh-nef] /ˈaɪ səˌnɛf/ noun, Meteorology. 1. a line on a weather map or chart connecting points having the same amount of cloudiness.
International Society of Nurses in Genetics
[ahy-suh-nahy-uh-zid] /ˌaɪ səˈnaɪ ə zɪd/ noun, Pharmacology. 1. a white, crystalline, water-soluble solid, C 6 H 7 N 3 O, used in the treatment of tuberculosis. /ˌaɪsəʊˈnaɪəzɪd/ noun 1. a soluble colourless crystalline compound used to treat tuberculosis. Formula: C6H7N3O isoniazid i·so·ni·a·zid (ī’sə-nī’ə-zĭd) n. An antibacterial compound used in the treatment of tuberculosis.