From Longman Dictionary of Contemporary Englishretentivere‧ten‧tive /rɪˈtentɪv/ AWL adjective REMEMBERa retentive memory or mind is able to hold facts and remember them → anal(2) —retentiveness noun [uncountable]
Examples from the Corpus
retentive• Soil should be rich and moisture retentive, but free-draining.• This gives a moisture retentive medium, but allows excess water to drain from the roots.• He had a highly retentive memory and was an accomplished and lively speaker.• He had a very retentive memory.• The pores between silt particles are so small and retentive of water that tightly packed silt can not be emptied by drainage. 