Diluted; containing extra water. / (colloquial, figuratively) Weakened or simplified

simple past tense and past participle of water down

To dilute; to add water to. / (idiomatic) To make weaker. / (idiomatic) To simplify or oversimplify; to make easier; to make less difficult. / (idiomatic) To make less restrictive; to make more lenient.

present participle of water down

Third-person singular simple present indicative form of water down