There are many synonyms for the phrase "lost in reverie." Some common ones include daydreaming, woolgathering, deep in thought, lost in thought, absorbed, engrossed, preoccupied, and contemplative. Other synonyms could include entranced, enchanted, entranced, spellbound, and rapt. These words all describe a state of mind where someone is absorbed in their thoughts or imagination, to the point where they may not be fully aware of their surroundings. It is a peaceful and reflective state, but one that can also be difficult to snap out of. Whatever word you choose, it describes a delightful state that can offer a much-needed escape from reality.