One hundred million words is a large enough corpus for many empirical strategies for learning about language, either for linguists and lexicographers (Baker, Fillmore, and Lowe 1998; Kilgarriff and Rundell 2002) or for technologies that need quantitative information about the behavior of words as input (most notably parsers [Briscoe and Carroll 1997;Korhonen 2000]).
for some purposes, it is not large enough.