re·tain 
(rĭ-tān)
(rĭ-tān)tr.v. re·tained, re·tain·ing, re·tains
1.
a. To keep possession of; continue to have: The family sold the house but retained the land. See Synonyms at keep.
b. To keep in a particular place or condition: a library that retains the author's papers; plants that retain a lot of water.
c. To continue to have as a feature or aspect: retains his good humor after all the setbacks.
2. To keep in mind; remember: retains the songs she learned in childhood.
3. To require (a student) to repeat a class or grade because of insufficient educational progress to advance.
4.
a. To keep in one's service or pay: retain employees on a workforce.
b. To hire (an attorney, for example) by the payment of a fee.
c. To hire someone for (his or her services).
[Middle English reteinen, from Old French retenir, from Latin retinēre : re-, re- + tenēre, to hold; see ten- in the Appendix of Indo-European roots.]
re·tain′a·bili·ty n.
re·taina·ble adj.
re·tainment n.