What is Assumption?

Legal Definition
The cause and effect connection that is accepted. It is used in simulations. It can be dangerous if accepted without any real world proof. Refer to critical thinking and rule of thumb.
Legal Definition
The act or agreement of assuming or taking upon one's self; the undertaking or adoption of a debt or obligation primarily resting upon another, as where the purchaser of real estate "assumes" a mortgage resting upon it, in which case he adopts the mortgage debt as his own and becomes personally liable for its payment. Eggleston v. Morrison. 84 III. App. 631; Locke v. Homer, 131 Mass. 93, 41 Am. Rep. 199; Springer v. De Wolf, 194 III. 218, 62 N. E. 542, 56 In R. A. 465, 88 Am. St Rep. 155; Lenz v. Railroad Co., Ill Wis. 198, 86 N. W. 607.

The difference between the purchaser of land assuming a mortgage on it and simply buying subject to the mortgage, is that in the former case he makes himself personally liable for the payment of the mortgage debt, while in the lat ter case he does not. Hancock v. Fleming, 103 Ind 533, 3 N. E. 254; Braman v. Dowse, 12 Cush. (Mass.) 227.

Where one "assumes" a lease, he takes to himself the obligations, contracts, agreements, and benefits to which the other Contracting party was entitled under the terms of the lease. Cincinnati, etc., R. Co. v. Indiana, etc., R. Co.., 44 Ohio St. 287, 314, 7 N. El 152. See Assumption of risk.
-- Black's Law Dictionary