A word is defined as a continuous string of alphanumeric characters. These are the letters A-Z, a-z, numbers 0-9, and the Latin-1 alphanumeric characters). In most modes, any character which is not alphanumeric is treated as a word delimiter.
A sentence begins wherever a paragraph or previous sentence ends. The end of a sentence is defined as consisting of a sentence terminating character followed by two spaces or a newline. Two spaces are required to prevent abbreviations (such as Mr.) from being taken as the end of a sentence. Such abbreviations at the end of a line are taken as the end of a sentence. There may also be any number of closing delimiter characters between the sentence terminating character and the spaces or newline.
LispWorks Editor User Guide (Unix version) - 9 Dec 2014