Abstract
<jats:p>Linguistic changes often diffuse through the lexicon, spreading from word to word. The direction of diffusion depends on word frequency and the mechanisms driving the change. This entry critically reviews research on frequency effects in language change from a usage‐based perspective. Reductive sound changes are argued to affect frequent words first. In contrast to much current literature, it is argued that the frequency effect need not increase when the change accelerates for this explanation to hold. Frequent words are also argued to be more likely to be extended to novel uses, because of their higher accessibility. This accounts for certain kinds of semantic change (e.g., the changes we see in grammaticalization) and morphological paradigm leveling. Analogical changes and those due to misperception are argued to preferentially target low‐frequency words. An important complication arises because words occur in contexts that either favor or disfavor a change. Words that frequently occur in change‐favoring contexts and infrequently occur in change‐disfavoring contexts are the words that are most likely to change and to change fastest. The direction of change in semantics depends almost entirely on the contexts in which the word occurs: words that frequently occur in a context that licenses a certain pragmatic inference can become associated with that inference, carrying it to other contexts. That is, social and linguistic contexts host bits of form and meaning that can stick to words (and other expressions) that appear frequently in those contexts. Current methodological issues with studying the role of frequency in lexical diffusion are summarized.</jats:p>