It is offered to consider word meanings changes in diachrony as
semicontinuous random walk with reflecting and swallowing screens. The basic
characteristics of word life cycle are defined. Verification of the model has
been realized on the data of Russian words distribution on various age periods.Comment: 4 pages, 1 table, 3 figures. Submitted to conference "Language in
  Sinchrony and Diachrony", to be held in Petrozavodsk State Pedagogical
  University (Russia), 15-17 October, 2001. (In Russian