The speech given by him seemed to be INNOCUOUS but there were undercurrents that implied the contrary:-

The ANTONYM of the word INNOCUOUS is:

The correct option is Harmful.

Step-by-step Explanation:

1. Understanding the word "Innocuous":
The word innocuous is derived from the Latin roots in- (meaning "not") and nocuus (meaning "hurtful"). Therefore, it literally translates to "not hurtful" or "harmless." It is commonly used to describe things that are safe, produce no ill effects, or are unlikely to offend or provoke anyone.

2. Analyzing the context:
In the given sentence, "The speech given by him seemed to be innocuous but there were undercurrents that implied the contrary," the word "contrary" signals a contrast. This indicates that while the speech appeared to be safe or harmless on the surface, the underlying tone or subtext actually suggested something damaging or negative.

3. Evaluating the options to find the Antonym (opposite meaning):
• Inoffensive: This word means causing no harm or offense, which is a synonym of innocuous, not an antonym.
• Harmful: This word means causing or capable of causing damage, injury, or hurt. Since innocuous means harmless, "harmful" is its direct opposite.
• Gentle: This means mild, moderate, or kind. While related to harmlessness, it does not serve as a direct, precise antonym for innocuous in this context.
• Insightful: This means exhibiting clear or deep perception. It is completely unrelated to the concept of harm or safety.

Therefore, Harmful is the correct antonym of the word INNOCUOUS.