BECAUSE SCIENCE AND TECHNOLOGY have had so profound impact on our society, it should come as no surprise that they are the source in recent years of growing number of popular senses and words.' Many of these new words and meanings have been well covered by dictionaries although they may be condemned by the authors of usage guides; however, popular meanings that appear to conflict with the imposed scientific ones are conspicuously absent from some or all of the major American dictionaries. Dictionaries have outgrown the idea that commonplace misuses should be ignored lest they contaminate the uncorrupted; they have even gotten over their abhorrence of taboo words; but they still appear reluctant to accord full and fair treatment to popular meanings of scientific words. At best their policy is inconsistent, policy I hope the following examples will help to illustrate. CATALYST. A Supplement to the Oxford English Dictionary defines catalyst as a substance which when present in small amounts increases the rate of chemical reaction or process but which is chemically unchanged by the reaction; catalytic agent. This is the standard chemical meaning that every dictionary includes as the imposed meaning. As early as 1944, however, note in American Speech (19: 46) pointed out that catalysis and catalyst were often used figuratively, although no figurative uses were actually cited. Of all the major contemporary American dictionaries, only Webster's New World, 2d college edition, includes the now commonly used meaning. Every other dictionary links it to the imposed meaning of catalysis either directly or indirectly. For example, Webster's New Collegiate Dictionary, 8th edition, defines the extended sense of catalysis (to which the reader is referred from catalyst) as an action or reaction between two or more persons or forces precipitated by separate agent and esp. by one that is essentially unaltered by the The figurative or extracted meaning does not ordinarily imply that the person or thing precipitating reaction is itself unchanged by the reaction. Note the following citations.