What term describes the act of neglecting a legal right for a period sufficient to imply that the right has been waived?

The term that best describes the act of neglecting a legal right for a period sufficient to imply that the right has been waived is "acquiescence." Acquiescence occurs when a party knowingly allows another party to act in a certain way without objection over a significant period of time, which can imply consent or acceptance of the situation.

In legal contexts, this is important because it can affect one’s rights and how they can assert those rights later on. For example, if a property owner observes a neighbor using their property without permission for an extended time and does nothing to stop it, the property owner might be seen as acquiescing to that use, potentially undermining future claims to ownership or use of that property.

In contrast, abandonment refers to the decision to relinquish a property right entirely without any intention of reclaiming it, while waiver specifically involves the intentional relinquishment of a known right, demonstrating a conscious choice rather than a passive implication. Retention doesn't pertain to the concept of neglect or inaction related to rights but rather suggests keeping or holding onto something.