imagining — to form a mental image of (something not actually present to the senses).
dreaming — (often initial capital letter) the ancient time of the creation of all things by sacred ancestors, whose spirits continue into the present, as conceived in the mythology of the Australian Aborigines.
dreamy — of the nature of or characteristic of dreams; visionary.
woolgathering — indulgence in idle fancies and in daydreaming; absentmindedness: His woolgathering was a handicap in school.
pensive — dreamily or wistfully thoughtful: a pensive mood.
wandering — moving from place to place without a fixed plan; roaming; rambling: wandering tourists.
lost in thought — Being preoccupied with one's thoughts rather than paying attention to reality.
distant — far off or apart in space; not near at hand; remote or removed (often followed by from): a distant place; a town three miles distant from here.
unmindful — not mindful; unaware; heedless; forgetful; careless; neglectful: unmindful of obligations.