busy
engaged
filled
in use
inhabited
absorbed
absorbed in
abstracted
at it
at work
buried in
buried in thought
caught up in
colonized
contemplating
contemplative
devoted
devoted to
empeopled
employed
engaged in thought
engrossed
engrossed in
engrossed in thought
full of business
hard at it
hard at work
immersed in
immersed in thought
in harness
intent
intent on
introspective
involved
lost in
lost in thought
meditating
meditative
monomaniacal
monopolized
obsessed
on duty
on the go
on the hop
on the job
on the jump
on the move
on the run
peopled
preoccupied
unoccupied
indolent