| social class | A stratum of people with similar position and prestige; includes social stratification. Social class is measured by criteria such as education, occupation, and income. (12 Dec 1998) |
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| stream class | Classification of streams based on the present and foreseeable uses made of the water, and the potential effects of on-site changes on downstream uses. Four classes are defined (05 Dec 1998) |
| immunoglobulin class switching | Gene rearrangement of the b-lymphocyte which results in a substitution in the type of heavy-chain constant region that is expressed. This allows the effector response to change while the antigen binding specificity (variable region) remains the same. The majority of class switching occurs by a DNA recombination event but it also can take place at the level of RNA processing. (12 Dec 1998) |
| first-class | Of the best class; of the highest rank; in the first division; of the best quality; first-rate; as, a first-class telescope. First-class car or First-class railway carriage, any passenger car of the highest regular class, and intended for passengers who pay the highest regular rate; distinguished from a second-class car. Source: Websters Dictionary (01 Mar 1998) |