There are many synonyms available for the phrase "was preoccupied." Some of the most common ones include "was lost in thought," "was engrossed," "was absorbed," "was distracted," "was preoccupied with," and "was immersed." Each of these synonyms carries a slightly different connotation and can be used in different situations. For example, "was lost in thought" may suggest a deeper level of introspection or reflection, while "was distracted" may suggest a more fleeting or temporary form of preoccupation. Ultimately, the choice of which phrase to use will depend on the context and the writer's desired tone and emphasis.