What does "inaudible" mean?

The term "inaudible" is defined as something that is "too quiet to be heard." This choice captures the essence of the word, which is derived from the prefix "in-" (not) and "audible" (able to be heard). Inaudible sounds can be so faint that they cannot be detected by the human ear, making this definition precise and appropriate.

The other options represent different characteristics of sound that do not align with the meaning of "inaudible." For instance, "clearly heard" presents the opposite condition, while "unintelligible due to noise" suggests a scenario where something is loud enough to hear but is not understandable, which differs from being inaudible. The description "soft but distinct" implies that a sound can be heard albeit at a low volume, which contradicts the notion of being inaudible entirely. Thus, the selected answer accurately reflects the meaning of the word in question.