What is the best definition for the word intangible?

The best definition for the word intangible is "vague." Intangible refers to something that cannot be touched or physically measured; it often relates to concepts, qualities, or states that are not easily perceived or understood. For example, emotions like love or happiness are intangible because they do not have a physical form and can be difficult to define clearly.

In contrast, the other options describe qualities that do not align with the essence of what intangible signifies. "Sudden" refers to something happening quickly or unexpectedly, while "forthright" denotes directness in speech or behavior. "Definite" signifies clarity or a clear outline, which is the opposite of the vague nature associated with the term intangible. Thus, "vague" effectively captures the elusive and non-physical qualities of things described as intangible.