Verb

To form into one whole; to make entire; to complete; to renew; to restore; to perfect.

To indicate the whole of; to give the sum or total of; as, an integrating anemometer, one that indicates or registers the entire action of the wind in a given time.

(mathematics) To subject to the operation of integration; to find the integral of.

To desegregate, as a school or neighborhood.

Verb

(en verb)

To keep in possession or use.

* Milton

Be obedient, and retain / Unalterably firm his love entire.

* 1856 : (Gustave Flaubert), (Madame Bovary), Part III Chapter XI, translated by Eleanor Marx-Aveling

A strange thing was that Bovary, while continually thinking of Emma, was forgetting her. He grew desperate as he felt this image fading from his memory in spite of all efforts to retain it. Yet every night he dreamt of her; it was always the same dream. He drew near her, but when he was about to clasp her she fell into decay in his arms.

* {{quote-book, year=1963, author=(Margery Allingham)

, title=(The China Governess) , chapter=1 citation , passage=The original family who had begun to build a palace to rival Nonesuch had died out before they had put up little more than the gateway, so that the actual structure which had come down to posterity retained the secret magic of a promise rather than the overpowering splendour of a great architectural achievement.}}

To keep in one's pay or service.

* Addison

A Benedictine convent has now retained the most learned father of their order to write in its defence.

To employ by paying a retainer.

To hold secure.

(obsolete) To restrain; to prevent.

(obsolete) To belong; to pertain.

* Boyle

A somewhat languid relish, retaining to bitterness.