What term means a serious or passionate request?

The term that accurately describes a serious or passionate request is "plea." A plea often carries an emotional weight, implying a sense of urgency or desperation that may accompany the request. It is commonly used in contexts such as legal situations, humanitarian appeals, or personal requests where the speaker aims to elicit sympathy or prompt action.

In contrast, the other terms do not convey the same meaning: "pivotal" refers to something of central importance or crucial as a turning point; "portent" denotes a sign or warning that indicates future events, often in a foreboding manner; and "plod" describes a manner of walking slowly or laboriously, which is unrelated to making a request. Thus, the choice of "plea" aligns best with the definition of a serious or passionate request.