To assume means to undertake. Generally, in legal contexts, to assume means to take over a certain duty or responsibility. For example, Alice may assume Bob’s liability for a debt (Alice may take over Bob’s debt).
In bankruptcy proceedings, “assume or reject” means to make an election under the Bankruptcy Code concerning a contract or an unexpired real property lease. For more details, see Bankruptcy Code § 365 (11 U.S. Code § 365 – Executory Contracts and Unexpired Leases) and Federal Rules of Bankruptcy Procedure Rule 6006. Assumption, Rejection or Assignment of an Executory Contract or Unexpired Lease.
In more common parlance, to assume may also mean to suppose as a fact; or to take for granted without substantiating evidence or proof.
[Last updated in June of 2021 by the Wex Definitions Team]