American English and British English vocabularies have diverged over time, resulting in lexical differences that have the potential to confound English-language intercultural communication. The differences derive from the need to adapt the meanings of existing expressions or to find new expressions for different things and to borrow expressions from different cultures. Separation and slow means of communication also cause differences and encourage one side, to retain archaic expressions that others have abandoned or modified. The differences in vocabulary can be grouped into four categories: the same expression with differences in style, connotation, and/or frequency; the same expression with one or more shared and different meanings; the same expression with completely different meaning; and different expressions with the same shared meaning. These differences in vocabularies affect understanding of all varieties of English. To bridge differences in English-language vocabularies, international business communication teachers and trainers must devote more attention to English as the dominant language of international business, create awareness of important vocabulary differences that have the potential to confound intercultural communication, and develop and teach strategies for bridging the vocabulary differences of English speakers