1. The first stage of tumor induction by a carcinogen; subtle alteration of cells by exposure to a carcinogenic agent so that they are likely to form a tumor upon subsequent exposure to a promoting agent (promotion). 2. Starting point of replication or translation in macromolecule biosynthesis. 3. Start of chemical or enzymatic reaction. 4. The first step in a chain reaction.

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(in oncology) the first step in the development of cancer (see carcinogenesis).

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ini·ti·a·tion (ĭ-nĭ″she-aґshən) in toxicology, the creation of a small alteration in the genetic makeup of a cell by a low level of exposure to a carcinogen; the cell may later become neoplastic upon repeated exposure to the same carcinogen or exposure to a promoter.

Medical dictionary. 2011.

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  • INITIATION — L’emploi du terme «initiation» s’est généralisé aujourd’hui pour signifier le fait de mettre au courant un individu aussi bien d’une science, d’un art que d’une profession (par exemple: initiation aux mathématiques), alors qu’il désignait… …   Encyclopédie Universelle

  • Initiation — bezeichnet die Einführung eines Außenstehenden (eines Anwärters) in eine Gemeinschaft oder seinen Aufstieg in einen anderen persönlichen Seinszustand, beispielsweise vom Kind zum Erwachsenen, von der Novizin zur Nonne oder vom Laien zum Schamanen …   Deutsch Wikipedia

  • Initiation — In*i ti*a tion, n. [L. initiatio: cf. F. initiation.] [1913 Webster] 1. The act of initiating, or the process of being initiated or introduced; as, initiation into a society, into business, literature, etc. The initiation of courses of events.… …   The Collaborative International Dictionary of English

  • initiation — initiation, initiation rites Rituals associated with the passage from childhood to adulthood, from one age set to another, or the entry into membership of secret societies. Aspects of initiation influenced van Gennep s study of rites of passage …   Dictionary of sociology

  • initiation — 1580s, from M.Fr. initiation or directly from L. initiationem (nom. initiatio) participation in secret rites, noun of action from pp. stem of initiare originate, initiate, from initium (see INITIAL (Cf. initial)) …   Etymology dictionary

  • Initiation — (lat.), Einweihung, Einführung in eine Wissenschaft etc …   Meyers Großes Konversations-Lexikon

  • initiation — index admittance (acceptance), discipline (training), genesis, inception, inflow, installation …   Law dictionary

  • initiation — *beginning, genesis, rise Analogous words: starting or start, commencing or commencement (see corresponding verbs at BEGIN): introducing or introduction, entering or entrance (see corresponding verbs at ENTER) Contrasted words: finishing or… …   New Dictionary of Synonyms

  • initiation — [n] start, introduction admission, baptism, beginning, commencement, debut, enrollment, entrance, inaugural, inauguration, inception, indoctrination, induction, installation, instatement, investiture, preliminaries; concepts 221,386 Ant. close,… …   New thesaurus

  • initiation — [i nish΄ē ā′shən] n. [L initiatio] 1. an initiating or being initiated 2. the ceremony by which a person is initiated into a fraternity, club, etc …   English World dictionary

  • Initiation — Pour les articles homonymes, voir initiation (homonymie) et initiation chrétienne. Rituel d’initiation dans le Zoroastrisme Initiation (lat, initiatio, init …   Wikipédia en Français

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