Conducted 7 studies to determine lower bounds for the amount of lexical ambiguity of words used in English text. Two special types of ambiguity are described and quantified, and a refined method for quantifying the ambiguity of individual lexical units is presented. Results of the studies indicate that at least 32{\%} of the words used in English text were ambiguous; it is suggested, however, that this figure is probably conservative. Temporary word definitions established for special purposes occurred in 30{\%} of the sample of texts. (21 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)