Which of the following denotes the condition of being something?

The suffix "ness" is used to form nouns that denote a state or condition of being. It attaches to adjectives to express physical, emotional, or abstract qualities. For example, adding "ness" to "happy" forms "happiness," which refers to the condition or state of being happy. This makes "ness" specifically linked to describing a condition, which directly matches the requirement of the question.

Other options may relate to different forms of word creation but do not specifically denote a condition. For example, "ing" typically indicates a gerund or present participle form and does not inherently convey a state of being. Similarly, "ful" is used to form adjectives that indicate fullness, and "ment" creates nouns that often refer to an action or resulting state, but it is not explicitly about a condition of being.