lost in thought

preoccupied, meditating, deeply engrossed in thought

Synonyms and related words:
absent, absentminded, absorbed, abstracted, bemused, buried in thought, castle-building, daydreaming, daydreamy, dreaming, dreamy, drowsing, ecstatic, elsewhere, engaged in thought, engrossed, engrossed in thought, faraway, half-awake, immersed in thought, in a reverie, in the clouds, introspective, lost, meditative, mooning, moonraking, museful, musing, napping, nodding, oblivious, occupied, pensive, pipe-dreaming, preoccupied, rapt, somewhere else, stargazing, taken up, transported, unconscious, woolgathering, wrapped in thought
  

phrv. มัวแต่ครุ่นคิด