語言與人類的社會生活息息相關，它真實的呈現人類的生活型態（Labov 1972; Hymes 1964）。針對國語詞彙的發展，探討新詞產生的論著很豐富（李振傑 1990；姚榮松 1998；蘇新春 2003）。然而，在社會生活產生改變時，有些詞彙因少用或不用也漸漸衰退甚至消失。
本研究調查臺灣過去30年間衰退的詞彙，並找出詞彙衰退與社會發展之間的關聯，共收錄舊詞835條例。調查發現在語言結構方面，衰退或消失的舊詞具有五種特徵：字形罕用（如：怯葸、蠭起）、音節增加（如：市勢→市場趨勢）、詞形改變（如：鳩集→揪集）、合詞變化（如：竣事→完竣、完事）及詞序改變（掛高→高掛）。
此外，本研究發現導致詞彙衰退的社會因素主要有三種：因事物停用或罕用，導致名稱的衰退（如：捲菸、勒吐精、嗶吱、統房）；因立場或態度轉變而引起詞彙的改變（如：匪、偽權、寇）；因語言使用習慣的改變引起詞彙的改變（如：決鬬（鬥）、奸宄、鳩（揪）工）

Words have witnessed changes in human life and trails of human thinking patterns. However, their decline also shows that human seems to be leaving history behind more quickly, judging by the speed with which some of these words fall out of use. In regard to this phenomenon, this study aims to construct a corpus to store words which have been declining or outdated in Taiwan for the past three decades, and to investigate the relationship between the decline of these words, focus shifts, and changes of lifestyle in Taiwan society.
Data collected over the course of 12 months shows more than 800 political and economic related words have fallen out of use gradually or even have become obsolete in Taiwan over the past three decades. Preliminary study shows that these declined words can be classified into five categories according to their structures and meanings. In addition, the decline of these words is closely related to the development of social life. Based on data analyses, this phenomenon is believed to be caused by factors such as (1) words fall out of use when certain things and matters are no longer or rarely used or practiced; (2) words change due to changes of users’ positions and attitudes towards certain people/ matters; (3) words change due to the change of language use.