In the Paragraph Style Sheet set the H&J field for No Hyphenation. This will turn off hyphenation for all paragraphs using that style sheet. If you do the same thing for the Normal Paragraph Style Sheet, it set this for any new text entered that has no other style sheet applied.

In order to turn off hyphenation for a particular word without explicitly defining a hyphenation exception, you can select the specific word and go to Style > Character. In the Character Attributes dialog set Language to None. While the best practice is to use Hyphenations Exceptions for specific words, setting the value for a specific word in a specific project (i.e., locally rather than globally) will work for a single project file.