Meaning of RETENTION in English
/ rɪˈtenʃn; NAmE / noun [ U ] ( formal )
the action of keeping sth rather than losing it or stopping it :
The company needs to improve its training and retention of staff.
the action of keeping liquid, heat, etc. inside sth rather than letting it escape :
Eating too much salt can cause fluid retention.
the ability to remember things :
Visual material aids the retention of information.
—see also retain
late Middle English (denoting the power to retain something): from Old French , from Latin retentio(n-) , from retinere hold back, from re- back + tenere hold.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005