To engross the thoughts means to capture someone's attention to the point where they are entirely focused on one thing. There are many synonyms for this phrase, each with their unique connotations. Some possible alternatives include captivate, fascinate, absorb, immerse, preoccupy, monopolize, enthrall, and enchant. Depending on the context and desired tone, some synonyms may be more appropriate than others. For instance, captivate may be a good choice for describing an engaging story or person, while preoccupy might be more applicable when referring to an obsessed mind. Regardless of which synonym is chosen, all of them convey the same sense of complete attention and absorption.