absorbed
abstracted
buried in thought
cogitative
cognitive
concentrating
concentrative
conceptive
conceptual
conceptualized
contemplating
contemplative
deliberating
deliberative
engaged in thought
engrossed
engrossed in thought
excogitating
ideative
immersed in thought
lost in thought
meditating
meditative
mental
museful
musing
noetic
occupied
pensive
pondering
prehensive
preoccupied
rapt
reflecting
reflective
ruminant
ruminating
ruminative
self-conscious
self-examining
serious
sober
speculative
subjective
thinking
thought
thoughtful
wistful
wrapped in thought
introspect
introspection
introspectional
introspectively
introspectiveness
absent-minded
apprehensive
egoistic
inscrutable
intuitive
moody
observant
perceptive
perturb
reticent
secretive
somber
studious
unpractical
affective
anti-infective
collective
connective
convective
corrective
defective
detective
directive
effective
elective
ineffective
infective
invective
irrespective
objective
perspective
projective
prospective
protective
respective
retrospective
selective
associational