Identify the correct one-word substitute for: “A condition of disuse or inactivity.”

The correct option is Desuetude.

Explanation:

Let's understand the meaning of the given phrase and examine all the options:

• Desuetude: Refers to a state of disuse, cessation of use, or inactivity. Therefore, it is the exact one-word substitute for "A condition of disuse or inactivity."

• Interregnum: Refers to a period when normal government or authority is suspended, especially between successive reigns or regimes.

• Destitute: Refers to extremely poor and lacking the means to provide for oneself.

• Lethargy: Refers to a lack of energy and enthusiasm; abnormal drowsiness or sluggishness.

Hence, Desuetude is the correct choice.