Definition from Nolo’s Plain-English Law Dictionary

Being inactive. For tax purposes, "passive income" includes income produced without active effort or management, such as bank interest, stock dividends, trust profits, and rent (when there is no management involvement). In estate planning, a "passive trustee" is one who has no responsibilities other than to hold title or wait for an event that would activate the trust.

Definition provided by Nolo’s Plain-English Law Dictionary.