Open English Wordnet
Nouns
(n)apprehension, apprehensiveness, dreadfearful expectation or anticipation“the student looked around the examination room with apprehension”
(n)understanding, apprehension, discernment, savvythe cognitive condition of someone who understands“he has virtually no understanding of social cause and effect”
(n)apprehension, arrest, catch, collar, pinch, taking into custodythe act of apprehending (especially apprehending a criminal)“the policeman on the beat got credit for the collar”