Usage patterns
体格が貧弱だto have a poor/weak physique
He has such a weak build that he gets tired after just a little exercise.
語彙が貧弱だto have a poor/limited vocabulary
His vocabulary is so limited that he repeats the same words over and over.
貧弱な設備poor/inadequate facilities or equipment
This school's facilities are so poor that we can barely do any experiments.