What is Alienation?

Legal Definition
In property law, alienation is the capacity for a piece of property or a property right to be sold or otherwise transferred from one party to another. Although property is generally deemed to be alienable, it may be subject to restraints on alienation. In England under the feudal system, land was generally transferred by subinfeudation and alienation required licence from the overlord.

Aboriginal title is one example of inalienability (save to the Crown) in common law jurisdictions.
-- Wikipedia
Legal Definition
Estates. Alienation is an act whereby one man transfers the property and possession of lands, tenements, or other things, to another. It is commonly applied to lands or tenements, as to alien (that is, to convey) land in fee, in mortmain. Termes de la ley. See Co. Litt. 118 b; Cruise Dig. tit. 32, c. 1, 1-8.

2. Alienations may be made by deed; by matter of record; and by devise.

3. Alienations by deed may be made by original or primary conveyances, which are those by means of which the benefit or estate is created or first arises; by derivative or secondary conveyances, by which the benefit or esta te originally created, is enlarged, restrained, transferred, or extinguished. These are conveyances by the common law. To these may be added some conveyances which derive their force and operation from the statute of uses. The original conveyances are the following: 1. Feoffment; 2. Gift; 3. Grant; 4. Lease; 6. Exchange; 6. Partition. The derivative are, 7. Release; 8. Confirmation; 9. Surrender; 10. Assignment; 11. Defeasance. Those deriving their force from the statute of uses, are, 12. Covenants to stand seised to uses; 13. Bargains and sales; 14. Lease and release; 15. Deeds to lend or declare the uses of other more direct conveyances; 16. Deeds of revocation of uses. 2 Bl. Com. ch. 20. Vide Conveyance; Deed. Alienations by matter of record may be, 1. By private acts of the legislature; 2. By grants, as by patents of lands; 3. By fines; 4. By common recovery. Alienations may also be made by devise (q.v.)
-- Bouviers Law Dictionary
Legal Definition
Med. jur. The term alienation or mental alienation is a generic expression to express the different kinds of aberrations of the human understandiug. Dict. des Science Med. h. t.; 1 Beck's Med. Jur. 535.
-- Bouviers Law Dictionary
Legal Definition
In real property law. The transfer of the property and possession of lands, tenements or other things, from one person to another. Termes de la Ley. It is particularly applied to absolute conveyances of real property. Co.nover v. Mutual Ins. Co.., 1 N. Y. 290, 294.

The act by which the title to real estate is voluntarily resigned by one person to another apd accepted by the latter, in the forms prescribed by law. The voluntary and complete transfer from one person to another, involving the complete and absolute exclusion, out of him who alienates, of any remaining interest or particle of interest, in the thing transmitted; the complete transfer of the property and possession of lands, tenements, or other things to another. Orrell v. Bay Mfg. Co.., 83 Miss. 800, 36 South. 561, 70 In R. A. 881; Burbank v. Insurance Co.., 24 N. H. 558, 57 Am. Dec. 300; United States v. Schurz, 102 In S 378, 26 In Ed. 167; Vining v. Willis, 40 Kan. 609, 20 Pac. 232.

In medical jurisprudence. A generic term denoting the different kinds or forms of mental aberration or derangement. See Alienation office.
-- Black's Law Dictionary
Legal Definition
The transfer of title. See 47 Am. St. Rep. 741.
-- Ballentine's Law Dictionary